diff --git "a/llmeval-env/lib/python3.10/site-packages/transformers/models/big_bird/modeling_flax_big_bird.py" "b/llmeval-env/lib/python3.10/site-packages/transformers/models/big_bird/modeling_flax_big_bird.py"
new file mode 100644--- /dev/null
+++ "b/llmeval-env/lib/python3.10/site-packages/transformers/models/big_bird/modeling_flax_big_bird.py"
@@ -0,0 +1,2635 @@
+# coding=utf-8
+# Copyright 2021 The Google Flax Team Authors and The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import Callable, Optional, Tuple
+
+import flax
+import flax.linen as nn
+import jax
+import jax.numpy as jnp
+from flax.core.frozen_dict import FrozenDict, freeze, unfreeze
+from flax.linen import combine_masks, make_causal_mask
+from flax.linen import partitioning as nn_partitioning
+from flax.linen.attention import dot_product_attention_weights
+from flax.traverse_util import flatten_dict, unflatten_dict
+from jax import lax
+
+from ...modeling_flax_outputs import (
+    FlaxBaseModelOutputWithPastAndCrossAttentions,
+    FlaxBaseModelOutputWithPooling,
+    FlaxBaseModelOutputWithPoolingAndCrossAttentions,
+    FlaxCausalLMOutputWithCrossAttentions,
+    FlaxMaskedLMOutput,
+    FlaxMultipleChoiceModelOutput,
+    FlaxSequenceClassifierOutput,
+    FlaxTokenClassifierOutput,
+)
+from ...modeling_flax_utils import (
+    ACT2FN,
+    FlaxPreTrainedModel,
+    append_call_sample_docstring,
+    append_replace_return_docstrings,
+    overwrite_call_docstring,
+)
+from ...utils import ModelOutput, add_start_docstrings, add_start_docstrings_to_model_forward, logging
+from .configuration_big_bird import BigBirdConfig
+
+
+logger = logging.get_logger(__name__)
+
+_CHECKPOINT_FOR_DOC = "google/bigbird-roberta-base"
+_CONFIG_FOR_DOC = "BigBirdConfig"
+
+remat = nn_partitioning.remat
+
+
+@flax.struct.dataclass
+class FlaxBigBirdForPreTrainingOutput(ModelOutput):
+    """
+    Output type of [`BigBirdForPreTraining`].
+
+    Args:
+        prediction_logits (`jnp.ndarray` of shape `(batch_size, sequence_length, config.vocab_size)`):
+            Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax).
+        seq_relationship_logits (`jnp.ndarray` of shape `(batch_size, 2)`):
+            Prediction scores of the next sequence prediction (classification) head (scores of True/False continuation
+            before SoftMax).
+        hidden_states (`tuple(jnp.ndarray)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
+            Tuple of `jnp.ndarray` (one for the output of the embeddings + one for the output of each layer) of shape
+            `(batch_size, sequence_length, hidden_size)`.
+
+            Hidden-states of the model at the output of each layer plus the initial embedding outputs.
+        attentions (`tuple(jnp.ndarray)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
+            Tuple of `jnp.ndarray` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
+            sequence_length)`.
+
+            Attentions weights after the attention softmax, used to compute the weighted average in the self-attention
+            heads.
+    """
+
+    prediction_logits: jnp.ndarray = None
+    seq_relationship_logits: jnp.ndarray = None
+    hidden_states: Optional[Tuple[jnp.ndarray]] = None
+    attentions: Optional[Tuple[jnp.ndarray]] = None
+
+
+@flax.struct.dataclass
+class FlaxBigBirdForQuestionAnsweringModelOutput(ModelOutput):
+    """
+    Base class for outputs of question answering models.
+
+    Args:
+        start_logits (`jnp.ndarray` of shape `(batch_size, sequence_length)`):
+            Span-start scores (before SoftMax).
+        end_logits (`jnp.ndarray` of shape `(batch_size, sequence_length)`):
+            Span-end scores (before SoftMax).
+        pooled_output (`jnp.ndarray` of shape `(batch_size, hidden_size)`):
+            pooled_output returned by FlaxBigBirdModel.
+        hidden_states (`tuple(jnp.ndarray)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
+            Tuple of `jnp.ndarray` (one for the output of the embeddings + one for the output of each layer) of shape
+            `(batch_size, sequence_length, hidden_size)`.
+
+            Hidden-states of the model at the output of each layer plus the initial embedding outputs.
+        attentions (`tuple(jnp.ndarray)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
+            Tuple of `jnp.ndarray` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
+            sequence_length)`.
+
+            Attentions weights after the attention softmax, used to compute the weighted average in the self-attention
+            heads.
+    """
+
+    start_logits: jnp.ndarray = None
+    end_logits: jnp.ndarray = None
+    pooled_output: jnp.ndarray = None
+    hidden_states: Optional[Tuple[jnp.ndarray]] = None
+    attentions: Optional[Tuple[jnp.ndarray]] = None
+
+
+BIG_BIRD_START_DOCSTRING = r"""
+
+    This model inherits from [`FlaxPreTrainedModel`]. Check the superclass documentation for the generic methods the
+    library implements for all its model (such as downloading, saving and converting weights from PyTorch models)
+
+    This model is also a
+    [flax.linen.Module](https://flax.readthedocs.io/en/latest/api_reference/flax.linen/module.html) subclass. Use it as
+    a regular Flax linen Module and refer to the Flax documentation for all matter related to general usage and
+    behavior.
+
+    Finally, this model supports inherent JAX features such as:
+
+    - [Just-In-Time (JIT) compilation](https://jax.readthedocs.io/en/latest/jax.html#just-in-time-compilation-jit)
+    - [Automatic Differentiation](https://jax.readthedocs.io/en/latest/jax.html#automatic-differentiation)
+    - [Vectorization](https://jax.readthedocs.io/en/latest/jax.html#vectorization-vmap)
+    - [Parallelization](https://jax.readthedocs.io/en/latest/jax.html#parallelization-pmap)
+
+    Parameters:
+        config ([`BigBirdConfig`]): Model configuration class with all the parameters of the model.
+            Initializing with a config file does not load the weights associated with the model, only the
+            configuration. Check out the [`~FlaxPreTrainedModel.from_pretrained`] method to load the model weights.
+        dtype (`jax.numpy.dtype`, *optional*, defaults to `jax.numpy.float32`):
+            The data type of the computation. Can be one of `jax.numpy.float32`, `jax.numpy.float16` (on GPUs) and
+            `jax.numpy.bfloat16` (on TPUs).
+
+            This can be used to enable mixed-precision training or half-precision inference on GPUs or TPUs. If
+            specified all the computation will be performed with the given `dtype`.
+
+            **Note that this only specifies the dtype of the computation and does not influence the dtype of model
+            parameters.**
+
+            If you wish to change the dtype of the model parameters, see [`~FlaxPreTrainedModel.to_fp16`] and
+            [`~FlaxPreTrainedModel.to_bf16`].
+"""
+
+BIG_BIRD_INPUTS_DOCSTRING = r"""
+    Args:
+        input_ids (`numpy.ndarray` of shape `({0})`):
+            Indices of input sequence tokens in the vocabulary.
+
+            Indices can be obtained using [`AutoTokenizer`]. See [`PreTrainedTokenizer.encode`] and
+            [`PreTrainedTokenizer.__call__`] for details.
+
+            [What are input IDs?](../glossary#input-ids)
+        attention_mask (`numpy.ndarray` of shape `({0})`, *optional*):
+            Mask to avoid performing attention on padding token indices. Mask values selected in `[0, 1]`:
+
+            - 1 for tokens that are **not masked**,
+            - 0 for tokens that are **masked**.
+
+            [What are attention masks?](../glossary#attention-mask)
+        token_type_ids (`numpy.ndarray` of shape `({0})`, *optional*):
+            Segment token indices to indicate first and second portions of the inputs. Indices are selected in `[0,
+            1]`:
+
+            - 0 corresponds to a *sentence A* token,
+            - 1 corresponds to a *sentence B* token.
+
+            [What are token type IDs?](../glossary#token-type-ids)
+        position_ids (`numpy.ndarray` of shape `({0})`, *optional*):
+            Indices of positions of each input sequence tokens in the position embeddings. Selected in the range `[0,
+            config.max_position_embeddings - 1]`.
+        head_mask (`numpy.ndarray` of shape `({0})`, `optional):
+            Mask to nullify selected heads of the attention modules. Mask values selected in `[0, 1]`:
+
+            - 1 indicates the head is **not masked**,
+            - 0 indicates the head is **masked**.
+
+        return_dict (`bool`, *optional*):
+            Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
+
+"""
+
+
+class FlaxBigBirdEmbeddings(nn.Module):
+    """Construct the embeddings from word, position and token_type embeddings."""
+
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    # Copied from transformers.models.bert.modeling_flax_bert.FlaxBertEmbeddings.setup
+    def setup(self):
+        self.word_embeddings = nn.Embed(
+            self.config.vocab_size,
+            self.config.hidden_size,
+            embedding_init=jax.nn.initializers.normal(stddev=self.config.initializer_range),
+            dtype=self.dtype,
+        )
+        self.position_embeddings = nn.Embed(
+            self.config.max_position_embeddings,
+            self.config.hidden_size,
+            embedding_init=jax.nn.initializers.normal(stddev=self.config.initializer_range),
+            dtype=self.dtype,
+        )
+        self.token_type_embeddings = nn.Embed(
+            self.config.type_vocab_size,
+            self.config.hidden_size,
+            embedding_init=jax.nn.initializers.normal(stddev=self.config.initializer_range),
+            dtype=self.dtype,
+        )
+        self.LayerNorm = nn.LayerNorm(epsilon=self.config.layer_norm_eps, dtype=self.dtype)
+        self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
+
+    def __call__(self, input_ids, token_type_ids, position_ids, attention_mask, deterministic: bool = True):
+        # Embed
+        inputs_embeds = self.word_embeddings(input_ids.astype("i4"))
+        position_embeds = self.position_embeddings(position_ids.astype("i4"))
+        token_type_embeddings = self.token_type_embeddings(token_type_ids.astype("i4"))
+
+        if self.config.rescale_embeddings:
+            inputs_embeds *= self.config.hidden_size**0.5
+
+        # Sum all embeddings
+        hidden_states = inputs_embeds + token_type_embeddings + position_embeds
+
+        # Layer Norm
+        hidden_states = self.dropout(hidden_states, deterministic=deterministic)
+        hidden_states = self.LayerNorm(hidden_states)
+        return hidden_states
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertSelfAttention with Bert->BigBird
+class FlaxBigBirdSelfAttention(nn.Module):
+    config: BigBirdConfig
+    causal: bool = False
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    def setup(self):
+        self.head_dim = self.config.hidden_size // self.config.num_attention_heads
+        if self.config.hidden_size % self.config.num_attention_heads != 0:
+            raise ValueError(
+                "`config.hidden_size`: {self.config.hidden_size} has to be a multiple of `config.num_attention_heads` "
+                "                   : {self.config.num_attention_heads}"
+            )
+
+        self.query = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+        )
+        self.key = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+        )
+        self.value = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+        )
+
+        if self.causal:
+            self.causal_mask = make_causal_mask(
+                jnp.ones((1, self.config.max_position_embeddings), dtype="bool"), dtype="bool"
+            )
+
+    def _split_heads(self, hidden_states):
+        return hidden_states.reshape(hidden_states.shape[:2] + (self.config.num_attention_heads, self.head_dim))
+
+    def _merge_heads(self, hidden_states):
+        return hidden_states.reshape(hidden_states.shape[:2] + (self.config.hidden_size,))
+
+    @nn.compact
+    # Copied from transformers.models.bart.modeling_flax_bart.FlaxBartAttention._concatenate_to_cache
+    def _concatenate_to_cache(self, key, value, query, attention_mask):
+        """
+        This function takes projected key, value states from a single input token and concatenates the states to cached
+        states from previous steps. This function is slighly adapted from the official Flax repository:
+        https://github.com/google/flax/blob/491ce18759622506588784b4fca0e4bf05f8c8cd/flax/linen/attention.py#L252
+        """
+        # detect if we're initializing by absence of existing cache data.
+        is_initialized = self.has_variable("cache", "cached_key")
+        cached_key = self.variable("cache", "cached_key", jnp.zeros, key.shape, key.dtype)
+        cached_value = self.variable("cache", "cached_value", jnp.zeros, value.shape, value.dtype)
+        cache_index = self.variable("cache", "cache_index", lambda: jnp.array(0, dtype=jnp.int32))
+
+        if is_initialized:
+            *batch_dims, max_length, num_heads, depth_per_head = cached_key.value.shape
+            # update key, value caches with our new 1d spatial slices
+            cur_index = cache_index.value
+            indices = (0,) * len(batch_dims) + (cur_index, 0, 0)
+            key = lax.dynamic_update_slice(cached_key.value, key, indices)
+            value = lax.dynamic_update_slice(cached_value.value, value, indices)
+            cached_key.value = key
+            cached_value.value = value
+            num_updated_cache_vectors = query.shape[1]
+            cache_index.value = cache_index.value + num_updated_cache_vectors
+            # causal mask for cached decoder self-attention: our single query position should only attend to those key positions that have already been generated and cached, not the remaining zero elements.
+            pad_mask = jnp.broadcast_to(
+                jnp.arange(max_length) < cur_index + num_updated_cache_vectors,
+                tuple(batch_dims) + (1, num_updated_cache_vectors, max_length),
+            )
+            attention_mask = combine_masks(pad_mask, attention_mask)
+        return key, value, attention_mask
+
+    def __call__(
+        self,
+        hidden_states,
+        attention_mask,
+        layer_head_mask,
+        key_value_states: Optional[jnp.ndarray] = None,
+        init_cache: bool = False,
+        deterministic=True,
+        output_attentions: bool = False,
+    ):
+        # if key_value_states are provided this layer is used as a cross-attention layer
+        # for the decoder
+        is_cross_attention = key_value_states is not None
+        batch_size = hidden_states.shape[0]
+
+        # get query proj
+        query_states = self.query(hidden_states)
+        # get key, value proj
+        if is_cross_attention:
+            # cross_attentions
+            key_states = self.key(key_value_states)
+            value_states = self.value(key_value_states)
+        else:
+            # self_attention
+            key_states = self.key(hidden_states)
+            value_states = self.value(hidden_states)
+
+        query_states = self._split_heads(query_states)
+        key_states = self._split_heads(key_states)
+        value_states = self._split_heads(value_states)
+
+        # handle cache prepare causal attention mask
+        if self.causal:
+            query_length, key_length = query_states.shape[1], key_states.shape[1]
+            if self.has_variable("cache", "cached_key"):
+                mask_shift = self.variables["cache"]["cache_index"]
+                max_decoder_length = self.variables["cache"]["cached_key"].shape[1]
+                causal_mask = lax.dynamic_slice(
+                    self.causal_mask, (0, 0, mask_shift, 0), (1, 1, query_length, max_decoder_length)
+                )
+            else:
+                causal_mask = self.causal_mask[:, :, :query_length, :key_length]
+            causal_mask = jnp.broadcast_to(causal_mask, (batch_size,) + causal_mask.shape[1:])
+
+        # combine masks if needed
+        if attention_mask is not None and self.causal:
+            attention_mask = jnp.broadcast_to(jnp.expand_dims(attention_mask, axis=(-3, -2)), causal_mask.shape)
+            attention_mask = combine_masks(attention_mask, causal_mask)
+        elif self.causal:
+            attention_mask = causal_mask
+        elif attention_mask is not None:
+            attention_mask = jnp.expand_dims(attention_mask, axis=(-3, -2))
+
+        # During fast autoregressive decoding, we feed one position at a time,
+        # and cache the keys and values step by step.
+        if self.causal and (self.has_variable("cache", "cached_key") or init_cache):
+            key_states, value_states, attention_mask = self._concatenate_to_cache(
+                key_states, value_states, query_states, attention_mask
+            )
+
+        # Convert the boolean attention mask to an attention bias.
+        if attention_mask is not None:
+            # attention mask in the form of attention bias
+            attention_bias = lax.select(
+                attention_mask > 0,
+                jnp.full(attention_mask.shape, 0.0).astype(self.dtype),
+                jnp.full(attention_mask.shape, jnp.finfo(self.dtype).min).astype(self.dtype),
+            )
+        else:
+            attention_bias = None
+
+        dropout_rng = None
+        if not deterministic and self.config.attention_probs_dropout_prob > 0.0:
+            dropout_rng = self.make_rng("dropout")
+
+        attn_weights = dot_product_attention_weights(
+            query_states,
+            key_states,
+            bias=attention_bias,
+            dropout_rng=dropout_rng,
+            dropout_rate=self.config.attention_probs_dropout_prob,
+            broadcast_dropout=True,
+            deterministic=deterministic,
+            dtype=self.dtype,
+            precision=None,
+        )
+
+        # Mask heads if we want to
+        if layer_head_mask is not None:
+            attn_weights = jnp.einsum("...hqk,h->...hqk", attn_weights, layer_head_mask)
+
+        attn_output = jnp.einsum("...hqk,...khd->...qhd", attn_weights, value_states)
+        attn_output = attn_output.reshape(attn_output.shape[:2] + (-1,))
+
+        outputs = (attn_output, attn_weights) if output_attentions else (attn_output,)
+        return outputs
+
+
+class FlaxBigBirdBlockSparseAttention(nn.Module):
+    config: BigBirdConfig
+    block_sparse_seed: int = None
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.query = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            use_bias=self.config.use_bias,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+        )
+        self.key = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            use_bias=self.config.use_bias,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+        )
+        self.value = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            use_bias=self.config.use_bias,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+        )
+
+    @staticmethod
+    def transpose_for_scores(x, n_heads, head_size):
+        new_x_shape = x.shape[:-1] + (n_heads, head_size)
+        x = x.reshape(*new_x_shape)
+        return jnp.transpose(x, axes=(0, 2, 1, 3))
+
+    def __call__(
+        self,
+        hidden_states,
+        attention_mask,
+        deterministic=True,
+        output_attentions=False,
+    ):
+        n_heads = self.config.num_attention_heads
+        head_size = self.config.hidden_size // n_heads
+
+        blocked_encoder_mask, band_mask, from_mask, to_mask = self.create_masks_for_block_sparse_attn(
+            attention_mask, self.config.block_size
+        )
+
+        query_layer = self.transpose_for_scores(self.query(hidden_states), n_heads, head_size)
+        key_layer = self.transpose_for_scores(self.key(hidden_states), n_heads, head_size)
+        value_layer = self.transpose_for_scores(self.value(hidden_states), n_heads, head_size)
+
+        indices_prng_key = None
+        if not deterministic:
+            indices_prng_key = self.make_rng("indices")
+
+        attn_output, attn_weights = self.bigbird_block_sparse_attention(
+            query_layer,
+            key_layer,
+            value_layer,
+            band_mask,
+            from_mask,
+            to_mask,
+            blocked_encoder_mask,
+            blocked_encoder_mask,
+            n_heads,
+            head_size,
+            indices_prng_key=indices_prng_key,
+            deterministic=deterministic,
+            plan_from_length=None,
+            plan_num_rand_blocks=None,
+            output_attentions=output_attentions,
+        )
+
+        outputs = (attn_output, attn_weights) if output_attentions else (attn_output,)
+        return outputs
+
+    @staticmethod
+    def create_masks_for_block_sparse_attn(attention_mask, block_size: int):
+        batch_size, seq_length = attention_mask.shape
+        if seq_length % block_size != 0:
+            raise ValueError(
+                f"Sequence length must be multiple of block size, but sequence length is {seq_length}, while block"
+                f" size is {block_size}."
+            )
+
+        def create_band_mask_from_inputs(from_blocked_mask, to_blocked_mask):
+            """
+            Create 3D attention mask from a 2D tensor mask.
+
+            Args:
+                from_blocked_mask: 2D Tensor of shape [batch_size,
+                from_seq_length//from_block_size, from_block_size].
+                to_blocked_mask: int32 Tensor of shape [batch_size,
+                to_seq_length//to_block_size, to_block_size].
+
+            Returns:
+                float Tensor of shape [batch_size, 1, from_seq_length//from_block_size-4, from_block_size,
+                3*to_block_size].
+            """
+            exp_blocked_to_pad = jnp.concatenate(
+                [to_blocked_mask[:, 1:-3], to_blocked_mask[:, 2:-2], to_blocked_mask[:, 3:-1]], axis=2
+            )
+            band_mask = jnp.einsum("blq,blk->blqk", from_blocked_mask[:, 2:-2], exp_blocked_to_pad)
+            band_mask = jnp.expand_dims(band_mask, 1)
+            return band_mask
+
+        blocked_encoder_mask = attention_mask.reshape(batch_size, seq_length // block_size, block_size)
+        band_mask = create_band_mask_from_inputs(blocked_encoder_mask, blocked_encoder_mask)
+
+        from_mask = attention_mask.reshape(batch_size, 1, seq_length, 1)
+        to_mask = attention_mask.reshape(batch_size, 1, 1, seq_length)
+
+        return blocked_encoder_mask, band_mask, from_mask, to_mask
+
+    def bigbird_block_sparse_attention(
+        self,
+        query_layer,
+        key_layer,
+        value_layer,
+        band_mask,
+        from_mask,
+        to_mask,
+        from_blocked_mask,
+        to_blocked_mask,
+        n_heads,
+        head_size,
+        indices_prng_key: Optional[jax.random.PRNGKey] = None,
+        deterministic: Optional[bool] = True,
+        plan_from_length=None,
+        plan_num_rand_blocks=None,
+        output_attentions=None,
+    ):
+        # BigBird block-sparse attention as suggested in paper
+
+        # ITC:
+        #     global tokens: 2 x block_size
+        #     window tokens: 3 x block_size
+        #     random tokens: num_rand_tokens x block_size
+
+        # ETC:
+        #     global tokens: extra_globals_tokens + 2 x block_size
+        #     window tokens: 3 x block_size
+        #     random tokens: num_rand_tokens x block_size
+
+        # Note:
+        #     1) Currently, ETC is not supported.
+        #     2) Window size is fixed to 3 blocks & it can be changed only by
+        #     changing `block_size`.
+        #     3) Number of global blocks are fixed (2 blocks here) & global tokens can be
+        #     controlled only by `block_size`.
+
+        # attention is calculated separately for q[0], q[1], q[2:-2], q[-2], q[-1] in order to use special trick of
+        # shifting tokens (for calculating sliding attention). hence following code can be divided into 5 parts.
+
+        bsz, _, from_seq_len, _ = query_layer.shape
+        to_seq_len = key_layer.shape[2]
+        from_block_size = to_block_size = self.config.block_size
+
+        if from_seq_len % from_block_size != 0:
+            raise ValueError("Query sided sequence length must be multiple of block size")
+
+        if to_seq_len % to_block_size != 0:
+            raise ValueError("Key/Value sided sequence length must be multiple of block size")
+
+        if from_seq_len // from_block_size != to_seq_len // to_block_size:
+            raise ValueError("Error the number of blocks needs to be same!")
+
+        n_rand_blocks = self.config.num_random_blocks
+        rsqrt_d = 1 / jnp.sqrt(head_size)
+        attn_mask_penalty = -10000.0
+
+        if from_seq_len in [1024, 3072, 4096]:  # old plans used in paper
+            max_seqlen = self.config.max_position_embeddings
+            rand_attn = [
+                self._bigbird_block_rand_mask(
+                    max_seqlen,
+                    max_seqlen,
+                    from_block_size,
+                    to_block_size,
+                    n_rand_blocks,
+                    indices_prng_key=indices_prng_key,
+                    deterministic=deterministic,
+                    last_idx=1024,
+                )[: (from_seq_len // from_block_size - 2)]
+                for _ in range(n_heads)
+            ]
+        else:
+            if plan_from_length is None:
+                plan_from_length, plan_num_rand_blocks = self._get_rand_attn_plan(
+                    from_seq_len, from_block_size, n_rand_blocks
+                )
+            rand_attn = self._bigbird_block_rand_mask_with_head(
+                from_seq_length=from_seq_len,
+                to_seq_length=to_seq_len,
+                from_block_size=from_block_size,
+                to_block_size=to_block_size,
+                num_heads=n_heads,
+                plan_from_length=plan_from_length,
+                plan_num_rand_blocks=plan_num_rand_blocks,
+                indices_prng_key=indices_prng_key,
+            )
+
+        rand_attn = jnp.stack(rand_attn, axis=0)
+        rand_attn = jnp.broadcast_to(rand_attn, (bsz,) + rand_attn.shape)
+
+        rand_mask = self._create_rand_mask_from_inputs(
+            from_blocked_mask, to_blocked_mask, rand_attn, n_heads, n_rand_blocks, bsz, from_seq_len, from_block_size
+        )
+
+        blocked_query_matrix = query_layer.reshape(bsz, n_heads, from_seq_len // from_block_size, from_block_size, -1)
+        blocked_key_matrix = key_layer.reshape(bsz, n_heads, to_seq_len // to_block_size, to_block_size, -1)
+        blocked_value_matrix = value_layer.reshape(bsz, n_heads, to_seq_len // to_block_size, to_block_size, -1)
+
+        shape = (bsz, n_heads, to_seq_len // to_block_size - 2, n_rand_blocks * to_block_size, -1)
+        gathered_key = self.jax_gather(blocked_key_matrix, rand_attn, batch_dims=2).reshape(*shape)
+        gathered_value = self.jax_gather(blocked_value_matrix, rand_attn, batch_dims=2).reshape(*shape)
+
+        # 1st PART
+        # 1st block (global block) attention scores
+        # q[0] x (k[0], k[1], k[2], k[3], k[4] .... )
+
+        # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, to_seq_len]
+        first_product = jnp.einsum("bhqd,bhkd->bhqk", blocked_query_matrix[:, :, 0], key_layer)
+
+        first_product = first_product * rsqrt_d
+        first_product += (1.0 - to_mask) * attn_mask_penalty
+        first_attn_weights = jax.nn.softmax(first_product, axis=-1)  # [bsz, n_heads, from_block_size, to_seq_len]
+
+        # [bsz, n_heads, from_block_size, to_seq_len] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, -1]
+        first_context_layer = jnp.einsum("bhqk,bhkd->bhqd", first_attn_weights, value_layer)
+        first_context_layer = jnp.expand_dims(first_context_layer, 2)
+
+        # 2nd PART
+        # 2nd block attention scores
+        # q[1] x (sliding_keys, random_keys, global_keys)
+        # sliding key blocks -> 2nd, 3rd blocks
+        # global key blocks -> 1st block
+
+        second_key_mat = jnp.concatenate(
+            [
+                blocked_key_matrix[:, :, 0],
+                blocked_key_matrix[:, :, 1],
+                blocked_key_matrix[:, :, 2],
+                blocked_key_matrix[:, :, -1],
+                gathered_key[:, :, 0],
+            ],
+            axis=2,
+        )  # [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1]
+        second_value_mat = jnp.concatenate(
+            [
+                blocked_value_matrix[:, :, 0],
+                blocked_value_matrix[:, :, 1],
+                blocked_value_matrix[:, :, 2],
+                blocked_value_matrix[:, :, -1],
+                gathered_value[:, :, 0],
+            ],
+            axis=2,
+        )  # [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1]
+
+        # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1]
+        # ==> [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size]
+        second_product = jnp.einsum("bhqd,bhkd->bhqk", blocked_query_matrix[:, :, 1], second_key_mat)
+        second_seq_pad = jnp.concatenate(
+            [
+                to_mask[:, :, :, : 3 * to_block_size],
+                to_mask[:, :, :, -to_block_size:],
+                jnp.ones([bsz, 1, 1, n_rand_blocks * to_block_size], dtype=to_mask.dtype),
+            ],
+            axis=3,
+        )
+        second_rand_pad = jnp.concatenate(
+            [
+                jnp.ones([bsz, n_heads, from_block_size, 4 * to_block_size], dtype=rand_mask.dtype),
+                rand_mask[:, :, 0],
+            ],
+            axis=3,
+        )
+        second_product = second_product * rsqrt_d
+        second_product += (1.0 - jnp.minimum(second_seq_pad, second_rand_pad)) * attn_mask_penalty
+        second_attn_weights = jax.nn.softmax(
+            second_product, axis=-1
+        )  # [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size]
+
+        # [bsz, n_heads, from_block_size, (4+r)*to_block_size] x [bsz, n_heads, (4+r)*to_block_size, -1]
+        #  ==> [bsz, n_heads, from_block_size, -1]
+        second_context_layer = jnp.einsum("bhqk,bhkd->bhqd", second_attn_weights, second_value_mat)
+        second_context_layer = jnp.expand_dims(second_context_layer, 2)
+
+        # 3rd PART
+        # Middle blocks attention scores
+        # q[-2:2] x (sliding_keys, random_keys, global_keys)
+        # sliding attn is calculated using special trick of shifting tokens as discussed in paper
+        # random keys are generated by taking random indices as per `rand_attn`
+        # global keys -> 1st & last block
+
+        exp_blocked_key_matrix = jnp.concatenate(
+            [blocked_key_matrix[:, :, 1:-3], blocked_key_matrix[:, :, 2:-2], blocked_key_matrix[:, :, 3:-1]], axis=3
+        )  # [bsz, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1]
+        exp_blocked_value_matrix = jnp.concatenate(
+            [blocked_value_matrix[:, :, 1:-3], blocked_value_matrix[:, :, 2:-2], blocked_value_matrix[:, :, 3:-1]],
+            axis=3,
+        )  # [bsz, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1]
+        middle_query_matrix = blocked_query_matrix[:, :, 2:-2]
+
+        # sliding attention scores for q[-2:2]
+        # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] x [b, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1]
+        inner_band_product = jnp.einsum("bhlqd,bhlkd->bhlqk", middle_query_matrix, exp_blocked_key_matrix)
+        #     ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, 3*to_block_size]
+        inner_band_product = inner_band_product * rsqrt_d
+
+        # randn attention scores for q[-2:2]
+        # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1]
+        # x [bsz, n_heads, from_seq_len//from_block_size-4, n_rand_blocks*to_block_size, -1]
+        rand_band_product = jnp.einsum("bhlqd,bhlkd->bhlqk", middle_query_matrix, gathered_key[:, :, 1:-1])
+        #     ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, n_rand_blocks*to_block_size]
+        rand_band_product = rand_band_product * rsqrt_d
+
+        # Including 1st block (since it's global)
+        # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] x [bsz, n_heads, to_block_size, -1]
+        #  ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size]
+        first_band_product = jnp.einsum("bhlqd,bhkd->bhlqk", middle_query_matrix, blocked_key_matrix[:, :, 0])
+        first_band_product = first_band_product * rsqrt_d
+
+        # Including last block (since it's global)
+        # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] x [bsz, n_heads, to_block_size, -1]
+        #  ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size]
+        last_band_product = jnp.einsum("bhlqd,bhkd->bhlqk", middle_query_matrix, blocked_key_matrix[:, :, -1])
+        last_band_product = last_band_product * rsqrt_d
+
+        # masking padded tokens
+        inner_band_product += (1.0 - band_mask) * attn_mask_penalty
+        first_band_product += (1.0 - jnp.expand_dims(to_mask[:, :, :, :to_block_size], 3)) * attn_mask_penalty
+        last_band_product += (1.0 - jnp.expand_dims(to_mask[:, :, :, -to_block_size:], 3)) * attn_mask_penalty
+        rand_band_product += (1.0 - rand_mask[:, :, 1:-1]) * attn_mask_penalty
+
+        # completing attention scores matrix for all q[-2:2]
+        band_product = jnp.concatenate(
+            [first_band_product, inner_band_product, rand_band_product, last_band_product], axis=-1
+        )  # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, (5+n_rand_blocks)*to_block_size]
+
+        # safely doing softmax since attention matrix is completed
+        attn_weights = jax.nn.softmax(
+            band_product, axis=-1
+        )  # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, (5+n_rand_blocks)*to_block_size]
+
+        # contribution of sliding keys
+        # [bsz, n_heads, m//from_block_size-4, from_block_size, 3*to_block_size]
+        # x [bsz, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1]
+        context_layer = jnp.einsum(
+            "bhlqk,bhlkd->bhlqd", attn_weights[:, :, :, :, to_block_size : 4 * to_block_size], exp_blocked_value_matrix
+        )
+        #     ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1]
+
+        # adding contribution of random keys
+        # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, n_rand_blocks*to_block_size]
+        # x [bsz, n_heads, from_seq_len//from_block_size-4, n_rand_blocks*to_block_size, -1]
+        context_layer += jnp.einsum(
+            "bhlqk,bhlkd->bhlqd",
+            attn_weights[:, :, :, :, 4 * to_block_size : -to_block_size],
+            gathered_value[:, :, 1:-1],
+        )
+        #     ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1]
+
+        # adding contribution of global keys
+        # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size] x [bsz, n_heads, to_block_size, -1]
+        #  ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1]
+        context_layer += jnp.einsum(
+            "bhlqk,bhkd->bhlqd", attn_weights[:, :, :, :, :to_block_size], blocked_value_matrix[:, :, 0]
+        )
+        # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size] x [bsz, n_heads, to_block_size, -1]
+        # ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1]
+        context_layer += jnp.einsum(
+            "bhlqk,bhkd->bhlqd", attn_weights[:, :, :, :, -to_block_size:], blocked_value_matrix[:, :, -1]
+        )
+
+        # 4th PART
+        # last 2nd token attention scores
+        # q[-2] x (sliding_keys, random_keys, global_keys)
+        # sliding key blocks -> last 3 blocks
+        # global key block -> 1st block
+        # random key block -> based on indices stored in `randn_attn`
+
+        second_last_key_mat = jnp.concatenate(
+            [
+                blocked_key_matrix[:, :, 0],
+                blocked_key_matrix[:, :, -3],
+                blocked_key_matrix[:, :, -2],
+                blocked_key_matrix[:, :, -1],
+                gathered_key[:, :, -1],
+            ],
+            axis=2,
+        )  # [bsz, n_heads, (4+n_random_blocks)*to_block_size, -1]
+        second_last_value_mat = jnp.concatenate(
+            [
+                blocked_value_matrix[:, :, 0],
+                blocked_value_matrix[:, :, -3],
+                blocked_value_matrix[:, :, -2],
+                blocked_value_matrix[:, :, -1],
+                gathered_value[:, :, -1],
+            ],
+            axis=2,
+        )  # [bsz, n_heads, (4+r)*to_block_size, -1]
+
+        # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1]
+        # ==> [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size]
+        second_last_product = jnp.einsum("bhqd,bhkd->bhqk", blocked_query_matrix[:, :, -2], second_last_key_mat)
+        second_last_seq_pad = jnp.concatenate(
+            [
+                to_mask[:, :, :, :to_block_size],
+                to_mask[:, :, :, -3 * to_block_size :],
+                jnp.ones([bsz, 1, 1, n_rand_blocks * to_block_size], dtype=to_mask.dtype),
+            ],
+            axis=3,
+        )
+        second_last_rand_pad = jnp.concatenate(
+            [
+                jnp.ones([bsz, n_heads, from_block_size, 4 * to_block_size], dtype=rand_mask.dtype),
+                rand_mask[:, :, -1],
+            ],
+            axis=3,
+        )
+        second_last_product = second_last_product * rsqrt_d
+        second_last_product += (1.0 - jnp.minimum(second_last_seq_pad, second_last_rand_pad)) * attn_mask_penalty
+        second_last_attn_weights = jax.nn.softmax(
+            second_last_product, axis=-1
+        )  # [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size]
+
+        # [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size] x [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1]
+        # ==> [bsz, n_heads, from_block_size, -1]
+        second_last_context_layer = jnp.einsum("bhqk,bhkd->bhqd", second_last_attn_weights, second_last_value_mat)
+        second_last_context_layer = jnp.expand_dims(second_last_context_layer, 2)
+
+        # 5th PART
+        # last block (global) attention scores
+        # q[-1] x (k[0], k[1], k[2], k[3], .... )
+
+        # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, to_seq_len]
+        last_product = jnp.einsum("bhqd,bhkd->bhqk", blocked_query_matrix[:, :, -1], key_layer)
+        last_product = last_product * rsqrt_d
+        last_product += (1.0 - to_mask) * attn_mask_penalty
+        last_attn_weights = jax.nn.softmax(last_product, axis=-1)  # [bsz, n_heads, from_block_size, n]
+
+        # [bsz, n_heads, from_block_size, to_seq_len] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, -1]
+        last_context_layer = jnp.einsum("bhqk,bhkd->bhqd", last_attn_weights, value_layer)
+        last_context_layer = jnp.expand_dims(last_context_layer, 2)
+
+        # combining representations of all tokens
+        context_layer = jnp.concatenate(
+            [first_context_layer, second_context_layer, context_layer, second_last_context_layer, last_context_layer],
+            axis=2,
+        )
+        context_layer = context_layer.reshape(bsz, n_heads, from_seq_len, -1) * from_mask
+        context_layer = jnp.transpose(context_layer, axes=(0, 2, 1, 3)).reshape(bsz, from_seq_len, -1)
+
+        attention_probs = None
+
+        return context_layer, attention_probs
+
+    @staticmethod
+    def jax_gather(params, indices, batch_dims=2):
+        """
+        Gather the indices from params correctly (equivalent to tf.gather but with modifications)
+
+        Args:
+            params: (bsz, n_heads, num_blocks, block_size, head_dim)
+            indices: (<num_blocks, 1)
+        """
+
+        def _jax_gather(params, indices):
+            return params[indices]
+
+        for _ in range(batch_dims):
+            _jax_gather = jax.vmap(_jax_gather, in_axes=(0, 0))
+
+        return _jax_gather(params, indices)  # params.shape[:batch_dims] + indices.shape + params.shape[batch_dims+1:]
+
+    def _create_rand_mask_from_inputs(
+        self,
+        from_blocked_mask,
+        to_blocked_mask,
+        broadcasted_rand_attn,
+        num_attention_heads,
+        num_random_blocks,
+        batch_size,
+        from_seq_length,
+        from_block_size,
+    ):
+        """
+        Create 3D attention mask from a 2D tensor mask.
+
+        Args:
+            from_blocked_mask: 2D Tensor of shape [batch_size, from_seq_length//from_block_size, from_block_size].
+            to_blocked_mask: int32 Tensor of shape [batch_size, to_seq_length//to_block_size, to_block_size].
+            broadcasted_rand_attn:
+                [batch_size, num_attention_heads, from_seq_length//from_block_size-2, num_rand_blocks]
+            num_attention_heads: int. Number of attention heads.
+            num_random_blocks: int. Number of random chunks per row.
+            batch_size: int. Batch size for computation.
+            from_seq_length: int. length of from sequence.
+            from_block_size: int. size of block in from sequence.
+
+        Returns:
+            float Tensor of shape [batch_size, num_attention_heads, from_seq_length//from_block_size-2,
+            from_block_size, num_rand_blocks*to_block_size].
+        """
+        num_windows = from_seq_length // from_block_size - 2
+        rand_mask = self.jax_gather(to_blocked_mask, broadcasted_rand_attn, batch_dims=1)
+        rand_mask = rand_mask.reshape(
+            batch_size, num_attention_heads, num_windows, num_random_blocks * from_block_size
+        )
+        rand_mask = jnp.einsum("blq,bhlk->bhlqk", from_blocked_mask[:, 1:-1], rand_mask)
+        return rand_mask
+
+    @staticmethod
+    def _get_rand_attn_plan(from_seq_length, from_block_size, num_rand_blocks):
+        """
+        Gives the plan of where to put random attention.
+
+        Args:
+            from_seq_length: int. length of from sequence.
+            from_block_size: int. size of block in from sequence.
+            num_rand_blocks: int. Number of random chunks per row.
+
+        Returns:
+            plan_from_length: ending location of from block plan_num_rand_blocks: number of random ending location for
+            each block
+        """
+
+        plan_from_length = []
+        plan_num_rand_blocks = []
+        if (2 * num_rand_blocks + 5) < (from_seq_length // from_block_size):
+            plan_from_length.append(int((2 * num_rand_blocks + 5) * from_block_size))
+            plan_num_rand_blocks.append(num_rand_blocks)
+            plan_from_length.append(from_seq_length)
+            plan_num_rand_blocks.append(0)
+        elif (num_rand_blocks + 5) < (from_seq_length // from_block_size):
+            plan_from_length.append(int((num_rand_blocks + 5) * from_block_size))
+            plan_num_rand_blocks.append(num_rand_blocks // 2)
+            plan_from_length.append(from_seq_length)
+            plan_num_rand_blocks.append(num_rand_blocks - (num_rand_blocks // 2))
+        else:
+            plan_from_length.append(from_seq_length)
+            plan_num_rand_blocks.append(num_rand_blocks)
+
+        return plan_from_length, plan_num_rand_blocks
+
+    @staticmethod
+    def _bigbird_block_rand_mask(
+        from_seq_length,
+        to_seq_length,
+        from_block_size,
+        to_block_size,
+        num_rand_blocks,
+        indices_prng_key: Optional[jax.random.PRNGKey] = None,
+        deterministic: Optional[bool] = True,
+        last_idx: Optional[int] = -1,
+    ):
+        """
+        Create adjacency list of random attention.
+
+        Args:
+            from_seq_length: int. length of from sequence.
+            to_seq_length: int. length of to sequence.
+            from_block_size: int. size of block in from sequence.
+            to_block_size: int. size of block in to sequence.
+            num_rand_blocks: int. Number of random chunks per row.
+            indices_prng_key: jax.random.PRNGKey. PRNG key that is used to perform random jax operations.
+            deterministic: bool. When False random attention will be used.
+            last_idx: if -1 then num_rand_blocks blocks chosen anywhere in to sequence,
+            if positive then num_rand_blocks blocks chosen only up to last_idx.
+
+        Returns:
+            adjacency list of size from_seq_length//from_block_size-2 by num_rand_blocks
+        """
+        # using this method when from_seq_length in [1024, 3072, 4096]
+
+        if from_seq_length // from_block_size != to_seq_length // to_block_size:
+            raise ValueError("Error the number of blocks needs to be same!")
+        rand_attn = jnp.zeros((from_seq_length // from_block_size - 2, num_rand_blocks), dtype=jnp.int32)
+        # deterministic nor randomness
+        if deterministic:
+            return rand_attn
+
+        middle_seq = jnp.arange(1, to_seq_length // to_block_size - 1, dtype=jnp.int32)
+        last = to_seq_length // to_block_size - 1
+        if last_idx > (2 * to_block_size):
+            last = (last_idx // to_block_size) - 1
+
+        r = num_rand_blocks  # shorthand
+        for i in range(1, from_seq_length // from_block_size - 1):
+            start = i - 2
+            end = i
+            if i == 1:
+                seq_values = jax.random.permutation(indices_prng_key, middle_seq[2:last])[:r]
+                rand_attn = rand_attn.at[i - 1].set(seq_values)
+            elif i == 2:
+                seq_values = jax.random.permutation(indices_prng_key, middle_seq[3:last])[:r]
+                rand_attn = rand_attn.at[i - 1].set(seq_values)
+            elif i == from_seq_length // from_block_size - 3:
+                seq_values = jax.random.permutation(indices_prng_key, middle_seq[:last])[:r]
+                rand_attn = rand_attn.at[i - 1].set(seq_values)
+            # Missing -3: should have been sliced till last-3
+            elif i == from_seq_length // from_block_size - 2:
+                seq_values = jax.random.permutation(indices_prng_key, middle_seq[:last])[:r]
+                rand_attn = rand_attn.at[i - 1].set(seq_values)
+            # Missing -4: should have been sliced till last-4
+            else:
+                if start > last:
+                    start = last
+                    seq_values = jax.random.permutation(indices_prng_key, middle_seq[:start])[:r]
+                    rand_attn = rand_attn.at[i - 1].set(seq_values)
+                elif (end + 1) == last:
+                    seq_values = jax.random.permutation(indices_prng_key, middle_seq[:start])[:r]
+                    rand_attn = rand_attn.at[i - 1].set(seq_values)
+                else:
+                    concat_values = jnp.concatenate((middle_seq[:start], middle_seq[end + 1 : last]))
+                    seq_values = jax.random.permutation(indices_prng_key, concat_values)[:r]
+                    rand_attn = rand_attn.at[i - 1].set(seq_values)
+        return rand_attn
+
+    def _bigbird_block_rand_mask_with_head(
+        self,
+        from_seq_length,
+        to_seq_length,
+        from_block_size,
+        to_block_size,
+        num_heads,
+        plan_from_length,
+        plan_num_rand_blocks,
+        indices_prng_key: Optional[jax.random.PRNGKey] = None,
+        deterministic: Optional[bool] = True,
+        window_block_left=1,
+        window_block_right=1,
+        global_block_top=1,
+        global_block_bottom=1,
+        global_block_left=1,
+        global_block_right=1,
+    ):
+        """
+        Create adjacency list of random attention.
+
+        Args:
+            from_seq_length: int. length of from sequence.
+            to_seq_length: int. length of to sequence.
+            from_block_size: int. size of block in from sequence.
+            to_block_size: int. size of block in to sequence.
+            num_heads: int. total number of heads.
+            plan_from_length: list. plan from length where num_random_blocks are choosen from.
+            plan_num_rand_blocks: list. number of rand blocks within the plan.
+            indices_prng_key: jax.random.PRNGKey. PRNG key that is used to perform random jax operations.
+            deterministic: bool. When False random attention will be used.
+            window_block_left: int. number of blocks of window to left of a block.
+            window_block_right: int. number of blocks of window to right of a block.
+            global_block_top: int. number of blocks at the top.
+            global_block_bottom: int. number of blocks at the bottom.
+            global_block_left: int. Number of blocks globally used to the left.
+            global_block_right: int. Number of blocks globally used to the right.
+
+        Returns:
+            adjacency list of size num_head where each element is of size from_seq_length//from_block_size-2 by
+            num_rand_blocks
+        """
+        # using this method when from_seq_length not in [1024, 3072, 4096]
+
+        if from_seq_length // from_block_size != to_seq_length // to_block_size:
+            raise ValueError("Error the number of blocks needs to be same!")
+
+        if from_seq_length not in plan_from_length:
+            raise ValueError("Error from sequence length not in plan!")
+
+        # Total number of blocks in the mmask
+        num_blocks = from_seq_length // from_block_size
+        # Number of blocks per plan
+        plan_block_length = jnp.array(plan_from_length) // from_block_size
+        # till when to follow plan
+        max_plan_idx = plan_from_length.index(from_seq_length)
+
+        # Random Attention adjacency list
+        rand_attn = [
+            jnp.zeros((num_blocks, sum(plan_num_rand_blocks[: max_plan_idx + 1])), dtype=jnp.int32)
+            for i in range(num_heads)
+        ]
+
+        # deterministic
+        if deterministic:
+            for nh in range(num_heads):
+                rand_attn[nh] = rand_attn[nh][global_block_top : num_blocks - global_block_bottom, :]
+            return rand_attn
+
+        # We will go iteratively over the plan blocks and pick random number of
+        # Attention blocks from the legally allowed blocks
+        for plan_idx in range(max_plan_idx + 1):
+            rnd_r_cnt = 0
+            if plan_idx > 0:
+                # set the row for all from_blocks starting from 0 to
+                # plan_block_length[plan_idx-1]
+                # column indx start fromm plan_block_length[plan_idx-1] and ends at
+                # plan_block_length[plan_idx]
+                if plan_num_rand_blocks[plan_idx] > 0:
+                    rnd_r_cnt = int(sum(plan_num_rand_blocks[:plan_idx]))
+                    curr_r_cnt = int(sum(plan_num_rand_blocks[: plan_idx + 1]))
+                    for blk_rw_idx in range(global_block_top, plan_block_length[plan_idx - 1]):
+                        for h in range(num_heads):
+                            single_block_row_attention = self._get_single_block_row_attention(
+                                block_id=blk_rw_idx,
+                                to_start_block_id=plan_block_length[plan_idx - 1],
+                                to_end_block_id=plan_block_length[plan_idx],
+                                num_rand_blocks=plan_num_rand_blocks[plan_idx],
+                                window_block_left=window_block_left,
+                                window_block_right=window_block_right,
+                                global_block_left=global_block_left,
+                                global_block_right=global_block_right,
+                                indices_prng_key=indices_prng_key,
+                            )
+                            rand_attn[h] = (
+                                rand_attn[h].at[blk_rw_idx, rnd_r_cnt:curr_r_cnt].set(single_block_row_attention)
+                            )
+
+                for pl_id in range(plan_idx):
+                    if plan_num_rand_blocks[pl_id] == 0:
+                        continue
+                    for blk_rw_idx in range(plan_block_length[plan_idx - 1], plan_block_length[plan_idx]):
+                        rnd_r_cnt = 0
+                        to_start_block_id = 0
+                        if pl_id > 0:
+                            rnd_r_cnt = int(sum(plan_num_rand_blocks[:pl_id]))
+                            to_start_block_id = plan_block_length[pl_id - 1]
+                        curr_r_cnt = int(sum(plan_num_rand_blocks[: pl_id + 1]))
+                        for h in range(num_heads):
+                            single_block_row_attention = self._get_single_block_row_attention(
+                                block_id=blk_rw_idx,
+                                to_start_block_id=to_start_block_id,
+                                to_end_block_id=plan_block_length[pl_id],
+                                num_rand_blocks=plan_num_rand_blocks[pl_id],
+                                window_block_left=window_block_left,
+                                window_block_right=window_block_right,
+                                global_block_left=global_block_left,
+                                global_block_right=global_block_right,
+                                indices_prng_key=indices_prng_key,
+                            )
+                            rand_attn[h] = (
+                                rand_attn[h].at[blk_rw_idx, rnd_r_cnt:curr_r_cnt].set(single_block_row_attention)
+                            )
+
+            if plan_num_rand_blocks[plan_idx] == 0:
+                continue
+            curr_r_cnt = int(sum(plan_num_rand_blocks[: plan_idx + 1]))
+            from_start_block_id = global_block_top
+            to_start_block_id = 0
+            if plan_idx > 0:
+                rnd_r_cnt = int(sum(plan_num_rand_blocks[:plan_idx]))
+                from_start_block_id = plan_block_length[plan_idx - 1]
+                to_start_block_id = plan_block_length[plan_idx - 1]
+            for blk_rw_idx in range(from_start_block_id, plan_block_length[plan_idx]):
+                for h in range(num_heads):
+                    single_block_row_attention = self._get_single_block_row_attention(
+                        block_id=blk_rw_idx,
+                        to_start_block_id=to_start_block_id,
+                        to_end_block_id=plan_block_length[plan_idx],
+                        num_rand_blocks=plan_num_rand_blocks[plan_idx],
+                        window_block_left=window_block_left,
+                        window_block_right=window_block_right,
+                        global_block_left=global_block_left,
+                        global_block_right=global_block_right,
+                        indices_prng_key=indices_prng_key,
+                    )
+                    rand_attn[h] = rand_attn[h].at[blk_rw_idx, rnd_r_cnt:curr_r_cnt].set(single_block_row_attention)
+
+        for nh in range(num_heads):
+            rand_attn[nh] = rand_attn[nh][global_block_top : num_blocks - global_block_bottom, :]
+        return rand_attn
+
+    @staticmethod
+    def _get_single_block_row_attention(
+        block_id,
+        to_start_block_id,
+        to_end_block_id,
+        num_rand_blocks,
+        indices_prng_key: Optional[jax.random.PRNGKey] = None,
+        window_block_left=1,
+        window_block_right=1,
+        global_block_left=1,
+        global_block_right=1,
+    ):
+        """
+        For a single row block get random row attention.
+
+        Args:
+            block_id: int. block id of row.
+            to_start_block_id: int. random attention column start id.
+            to_end_block_id: int. random attention column end id.
+            num_rand_blocks: int. number of random blocks to be selected.
+            indices_prng_key: jax.random.PRNGKey. PRNG key that is used to perform random jax operations
+            window_block_left: int. number of blocks of window to left of a block.
+            window_block_right: int. number of blocks of window to right of a block.
+            global_block_left: int. Number of blocks globally used to the left.
+            global_block_right: int. Number of blocks globally used to the right.
+
+        Returns:
+            row containing the random attention vector of size num_rand_blocks.
+        """
+        # list of to_blocks from which to choose random attention
+        to_block_list = jnp.arange(to_start_block_id, to_end_block_id, dtype=jnp.int32)
+        # permute the blocks
+        perm_block = jax.random.permutation(indices_prng_key, to_block_list)
+
+        # illegal blocks for the current block id, using window
+        illegal_blocks = list(range(block_id - window_block_left, block_id + window_block_right + 1))
+
+        # Add blocks at the start and at the end
+        illegal_blocks.extend(list(range(global_block_left)))
+        illegal_blocks.extend(list(range(to_end_block_id - global_block_right, to_end_block_id)))
+
+        # The second from_block cannot choose random attention on second last to_block
+        if block_id == 1:
+            illegal_blocks.append(to_end_block_id - 2)
+
+        # The second last from_block cannot choose random attention on second to_block
+        if block_id == to_end_block_id - 2:
+            illegal_blocks.append(1)
+
+        selected_random_blocks = []
+
+        for i in range(to_end_block_id - to_start_block_id):
+            if perm_block[i] not in illegal_blocks:
+                selected_random_blocks.append(perm_block[i])
+            if len(selected_random_blocks) == num_rand_blocks:
+                break
+        return jnp.array(selected_random_blocks, dtype=jnp.int32)
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertSelfOutput with Bert->BigBird
+class FlaxBigBirdSelfOutput(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    def setup(self):
+        self.dense = nn.Dense(
+            self.config.hidden_size,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+            dtype=self.dtype,
+        )
+        self.LayerNorm = nn.LayerNorm(epsilon=self.config.layer_norm_eps, dtype=self.dtype)
+        self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
+
+    def __call__(self, hidden_states, input_tensor, deterministic: bool = True):
+        hidden_states = self.dense(hidden_states)
+        hidden_states = self.dropout(hidden_states, deterministic=deterministic)
+        hidden_states = self.LayerNorm(hidden_states + input_tensor)
+        return hidden_states
+
+
+class FlaxBigBirdAttention(nn.Module):
+    config: BigBirdConfig
+    layer_id: int = None
+    causal: bool = False
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        if self.config.attention_type == "original_full":
+            self.self = FlaxBigBirdSelfAttention(self.config, causal=self.causal, dtype=self.dtype)
+        elif self.config.attention_type == "block_sparse":
+            self.self = FlaxBigBirdBlockSparseAttention(self.config, block_sparse_seed=self.layer_id, dtype=self.dtype)
+        else:
+            raise ValueError(
+                f"Your `config.attention_type` is {self.config.attention_type} but it can either be `original_full` or"
+                " `block_sparse`"
+            )
+
+        self.output = FlaxBigBirdSelfOutput(self.config, dtype=self.dtype)
+
+    def __call__(
+        self,
+        hidden_states,
+        attention_mask,
+        layer_head_mask,
+        key_value_states=None,
+        init_cache=False,
+        deterministic=True,
+        output_attentions: bool = False,
+    ):
+        # Attention mask comes in as attention_mask.shape == (*batch_sizes, kv_length)
+        # FLAX expects: attention_mask.shape == (*batch_sizes, 1, 1, kv_length) such that it is broadcastable
+        # with attn_weights.shape == (*batch_sizes, num_heads, q_length, kv_length)
+        if self.config.attention_type == "original_full":
+            attn_outputs = self.self(
+                hidden_states,
+                attention_mask,
+                layer_head_mask=layer_head_mask,
+                key_value_states=key_value_states,
+                init_cache=init_cache,
+                deterministic=deterministic,
+                output_attentions=output_attentions,
+            )
+        else:
+            attn_outputs = self.self(
+                hidden_states,
+                attention_mask,
+                deterministic=deterministic,
+                output_attentions=output_attentions,
+            )
+        attn_output = attn_outputs[0]
+        hidden_states = self.output(attn_output, hidden_states, deterministic=deterministic)
+
+        outputs = (hidden_states,)
+
+        if output_attentions:
+            outputs += (attn_outputs[1],)
+
+        return outputs
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertIntermediate with Bert->BigBird
+class FlaxBigBirdIntermediate(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    def setup(self):
+        self.dense = nn.Dense(
+            self.config.intermediate_size,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+            dtype=self.dtype,
+        )
+        self.activation = ACT2FN[self.config.hidden_act]
+
+    def __call__(self, hidden_states):
+        hidden_states = self.dense(hidden_states)
+        hidden_states = self.activation(hidden_states)
+        return hidden_states
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertOutput with Bert->BigBird
+class FlaxBigBirdOutput(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    def setup(self):
+        self.dense = nn.Dense(
+            self.config.hidden_size,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+            dtype=self.dtype,
+        )
+        self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
+        self.LayerNorm = nn.LayerNorm(epsilon=self.config.layer_norm_eps, dtype=self.dtype)
+
+    def __call__(self, hidden_states, attention_output, deterministic: bool = True):
+        hidden_states = self.dense(hidden_states)
+        hidden_states = self.dropout(hidden_states, deterministic=deterministic)
+        hidden_states = self.LayerNorm(hidden_states + attention_output)
+        return hidden_states
+
+
+class FlaxBigBirdLayer(nn.Module):
+    config: BigBirdConfig
+    layer_id: int = None
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    def setup(self):
+        self.attention = FlaxBigBirdAttention(
+            self.config, layer_id=self.layer_id, causal=self.config.is_decoder, dtype=self.dtype
+        )
+        self.intermediate = FlaxBigBirdIntermediate(self.config, dtype=self.dtype)
+        self.output = FlaxBigBirdOutput(self.config, dtype=self.dtype)
+        if self.config.add_cross_attention:
+            self.crossattention = FlaxBigBirdAttention(self.config, causal=False, dtype=self.dtype)
+
+    # Copied from transformers.models.bert.modeling_flax_bert.FlaxBertLayer.__call__ with Bert->BigBird
+    def __call__(
+        self,
+        hidden_states,
+        attention_mask,
+        layer_head_mask,
+        encoder_hidden_states: Optional[jnp.ndarray] = None,
+        encoder_attention_mask: Optional[jnp.ndarray] = None,
+        init_cache: bool = False,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+    ):
+        # Self Attention
+        attention_outputs = self.attention(
+            hidden_states,
+            attention_mask,
+            layer_head_mask=layer_head_mask,
+            init_cache=init_cache,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+        )
+        attention_output = attention_outputs[0]
+
+        # Cross-Attention Block
+        if encoder_hidden_states is not None:
+            cross_attention_outputs = self.crossattention(
+                attention_output,
+                attention_mask=encoder_attention_mask,
+                layer_head_mask=layer_head_mask,
+                key_value_states=encoder_hidden_states,
+                deterministic=deterministic,
+                output_attentions=output_attentions,
+            )
+            attention_output = cross_attention_outputs[0]
+
+        hidden_states = self.intermediate(attention_output)
+        hidden_states = self.output(hidden_states, attention_output, deterministic=deterministic)
+
+        outputs = (hidden_states,)
+
+        if output_attentions:
+            outputs += (attention_outputs[1],)
+            if encoder_hidden_states is not None:
+                outputs += (cross_attention_outputs[1],)
+        return outputs
+
+
+class FlaxBigBirdLayerCollection(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        if self.gradient_checkpointing:
+            FlaxBigBirdCheckpointLayer = remat(FlaxBigBirdLayer, static_argnums=(5, 6, 7))
+            self.layers = [
+                FlaxBigBirdCheckpointLayer(self.config, layer_id=i, name=str(i), dtype=self.dtype)
+                for i in range(self.config.num_hidden_layers)
+            ]
+        else:
+            self.layers = [
+                FlaxBigBirdLayer(self.config, layer_id=i, name=str(i), dtype=self.dtype)
+                for i in range(self.config.num_hidden_layers)
+            ]
+
+    # Copied from transformers.models.bert.modeling_flax_bert.FlaxBertLayerCollection.__call__ with Bert->BigBird
+    def __call__(
+        self,
+        hidden_states,
+        attention_mask,
+        head_mask,
+        encoder_hidden_states: Optional[jnp.ndarray] = None,
+        encoder_attention_mask: Optional[jnp.ndarray] = None,
+        init_cache: bool = False,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        all_attentions = () if output_attentions else None
+        all_hidden_states = () if output_hidden_states else None
+        all_cross_attentions = () if (output_attentions and encoder_hidden_states is not None) else None
+
+        # Check if head_mask has a correct number of layers specified if desired
+        if head_mask is not None:
+            if head_mask.shape[0] != (len(self.layers)):
+                raise ValueError(
+                    f"The head_mask should be specified for {len(self.layers)} layers, but it is for                  "
+                    f"       {head_mask.shape[0]}."
+                )
+
+        for i, layer in enumerate(self.layers):
+            if output_hidden_states:
+                all_hidden_states += (hidden_states,)
+
+            layer_outputs = layer(
+                hidden_states,
+                attention_mask,
+                head_mask[i] if head_mask is not None else None,
+                encoder_hidden_states,
+                encoder_attention_mask,
+                init_cache,
+                deterministic,
+                output_attentions,
+            )
+
+            hidden_states = layer_outputs[0]
+
+            if output_attentions:
+                all_attentions += (layer_outputs[1],)
+
+                if encoder_hidden_states is not None:
+                    all_cross_attentions += (layer_outputs[2],)
+
+        if output_hidden_states:
+            all_hidden_states += (hidden_states,)
+
+        outputs = (hidden_states, all_hidden_states, all_attentions, all_cross_attentions)
+
+        if not return_dict:
+            return tuple(v for v in outputs if v is not None)
+
+        return FlaxBaseModelOutputWithPastAndCrossAttentions(
+            last_hidden_state=hidden_states,
+            hidden_states=all_hidden_states,
+            attentions=all_attentions,
+            cross_attentions=all_cross_attentions,
+        )
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertEncoder with Bert->BigBird
+class FlaxBigBirdEncoder(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.layer = FlaxBigBirdLayerCollection(
+            self.config,
+            dtype=self.dtype,
+            gradient_checkpointing=self.gradient_checkpointing,
+        )
+
+    def __call__(
+        self,
+        hidden_states,
+        attention_mask,
+        head_mask,
+        encoder_hidden_states: Optional[jnp.ndarray] = None,
+        encoder_attention_mask: Optional[jnp.ndarray] = None,
+        init_cache: bool = False,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        return self.layer(
+            hidden_states,
+            attention_mask,
+            head_mask=head_mask,
+            encoder_hidden_states=encoder_hidden_states,
+            encoder_attention_mask=encoder_attention_mask,
+            init_cache=init_cache,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertPredictionHeadTransform with Bert->BigBird
+class FlaxBigBirdPredictionHeadTransform(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.dense = nn.Dense(self.config.hidden_size, dtype=self.dtype)
+        self.activation = ACT2FN[self.config.hidden_act]
+        self.LayerNorm = nn.LayerNorm(epsilon=self.config.layer_norm_eps, dtype=self.dtype)
+
+    def __call__(self, hidden_states):
+        hidden_states = self.dense(hidden_states)
+        hidden_states = self.activation(hidden_states)
+        return self.LayerNorm(hidden_states)
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertLMPredictionHead with Bert->BigBird, np.ndarray->jnp.ndarray
+class FlaxBigBirdLMPredictionHead(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    bias_init: Callable[..., jnp.ndarray] = jax.nn.initializers.zeros
+
+    def setup(self):
+        self.transform = FlaxBigBirdPredictionHeadTransform(self.config, dtype=self.dtype)
+        self.decoder = nn.Dense(self.config.vocab_size, dtype=self.dtype, use_bias=False)
+        self.bias = self.param("bias", self.bias_init, (self.config.vocab_size,))
+
+    def __call__(self, hidden_states, shared_embedding=None):
+        hidden_states = self.transform(hidden_states)
+
+        if shared_embedding is not None:
+            hidden_states = self.decoder.apply({"params": {"kernel": shared_embedding.T}}, hidden_states)
+        else:
+            hidden_states = self.decoder(hidden_states)
+
+        bias = jnp.asarray(self.bias, self.dtype)
+        hidden_states += bias
+        return hidden_states
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertOnlyMLMHead with Bert->BigBird
+class FlaxBigBirdOnlyMLMHead(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.predictions = FlaxBigBirdLMPredictionHead(self.config, dtype=self.dtype)
+
+    def __call__(self, hidden_states, shared_embedding=None):
+        hidden_states = self.predictions(hidden_states, shared_embedding=shared_embedding)
+        return hidden_states
+
+
+class FlaxBigBirdPreTrainingHeads(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.predictions = FlaxBigBirdLMPredictionHead(self.config, dtype=self.dtype)
+        self.seq_relationship = nn.Dense(2, dtype=self.dtype)
+
+    def __call__(self, hidden_states, pooled_output, shared_embedding=None):
+        prediction_scores = self.predictions(hidden_states, shared_embedding=shared_embedding)
+        seq_relationship_score = self.seq_relationship(pooled_output)
+        return prediction_scores, seq_relationship_score
+
+
+class FlaxBigBirdPreTrainedModel(FlaxPreTrainedModel):
+    """
+    An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
+    models.
+    """
+
+    config_class = BigBirdConfig
+    base_model_prefix = "bert"
+    module_class: nn.Module = None
+
+    def __init__(
+        self,
+        config: BigBirdConfig,
+        input_shape: Optional[tuple] = None,
+        seed: int = 0,
+        dtype: jnp.dtype = jnp.float32,
+        _do_init: bool = True,
+        gradient_checkpointing: bool = False,
+        **kwargs,
+    ):
+        module = self.module_class(config=config, dtype=dtype, gradient_checkpointing=gradient_checkpointing, **kwargs)
+        if config.attention_type == "block_sparse" and input_shape is None:
+            input_shape = (1, 12 * config.block_size)
+        elif input_shape is None:
+            input_shape = (1, 1)
+
+        super().__init__(config, module, input_shape=input_shape, seed=seed, dtype=dtype, _do_init=_do_init)
+
+    # Copied from transformers.models.bert.modeling_flax_bert.FlaxBertPreTrainedModel.enable_gradient_checkpointing
+    def enable_gradient_checkpointing(self):
+        self._module = self.module_class(
+            config=self.config,
+            dtype=self.dtype,
+            gradient_checkpointing=True,
+        )
+
+    def init_weights(self, rng: jax.random.PRNGKey, input_shape: Tuple, params: FrozenDict = None) -> FrozenDict:
+        # init input tensors
+        input_ids = jnp.zeros(input_shape, dtype="i4")
+        token_type_ids = jnp.zeros_like(input_ids)
+        position_ids = jnp.broadcast_to(jnp.arange(jnp.atleast_2d(input_ids).shape[-1]), input_shape)
+        attention_mask = jnp.ones_like(input_ids)
+        head_mask = jnp.ones((self.config.num_hidden_layers, self.config.num_attention_heads))
+
+        params_rng, dropout_rng, indices_rng = jax.random.split(rng, num=3)
+        rngs = {"params": params_rng, "dropout": dropout_rng, "indices": indices_rng}
+
+        if self.config.add_cross_attention:
+            encoder_hidden_states = jnp.zeros(input_shape + (self.config.hidden_size,))
+            encoder_attention_mask = attention_mask
+            module_init_outputs = self.module.init(
+                rngs,
+                input_ids,
+                attention_mask,
+                token_type_ids,
+                position_ids,
+                head_mask,
+                encoder_hidden_states,
+                encoder_attention_mask,
+                return_dict=False,
+            )
+        else:
+            module_init_outputs = self.module.init(
+                rngs,
+                input_ids,
+                attention_mask,
+                token_type_ids,
+                position_ids,
+                head_mask,
+                return_dict=False,
+            )
+
+        random_params = module_init_outputs["params"]
+
+        if params is not None:
+            random_params = flatten_dict(unfreeze(random_params))
+            params = flatten_dict(unfreeze(params))
+            for missing_key in self._missing_keys:
+                params[missing_key] = random_params[missing_key]
+            self._missing_keys = set()
+            return freeze(unflatten_dict(params))
+        else:
+            return random_params
+
+    # Copied from transformers.models.bart.modeling_flax_bart.FlaxBartDecoderPreTrainedModel.init_cache
+    def init_cache(self, batch_size, max_length):
+        r"""
+        Args:
+            batch_size (`int`):
+                batch_size used for fast auto-regressive decoding. Defines the batch size of the initialized cache.
+            max_length (`int`):
+                maximum possible length for auto-regressive decoding. Defines the sequence length of the initialized
+                cache.
+        """
+        # init input variables to retrieve cache
+        input_ids = jnp.ones((batch_size, max_length), dtype="i4")
+        attention_mask = jnp.ones_like(input_ids, dtype="i4")
+        position_ids = jnp.broadcast_to(jnp.arange(jnp.atleast_2d(input_ids).shape[-1]), input_ids.shape)
+
+        init_variables = self.module.init(
+            jax.random.PRNGKey(0), input_ids, attention_mask, position_ids, return_dict=False, init_cache=True
+        )
+        return unfreeze(init_variables["cache"])
+
+    @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length"))
+    def __call__(
+        self,
+        input_ids,
+        attention_mask=None,
+        token_type_ids=None,
+        position_ids=None,
+        head_mask=None,
+        encoder_hidden_states=None,
+        encoder_attention_mask=None,
+        params: dict = None,
+        dropout_rng: Optional[jax.random.PRNGKey] = None,
+        indices_rng: Optional[jax.random.PRNGKey] = None,
+        train: bool = False,
+        output_attentions: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None,
+        past_key_values: dict = None,
+    ):
+        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
+        output_hidden_states = (
+            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
+        )
+        return_dict = return_dict if return_dict is not None else self.config.return_dict
+
+        # init input tensors if not passed
+        if token_type_ids is None:
+            token_type_ids = jnp.zeros_like(input_ids)
+
+        if position_ids is None:
+            position_ids = jnp.broadcast_to(jnp.arange(jnp.atleast_2d(input_ids).shape[-1]), input_ids.shape)
+
+        if attention_mask is None:
+            attention_mask = jnp.ones_like(input_ids)
+
+        if head_mask is None:
+            head_mask = jnp.ones((self.config.num_hidden_layers, self.config.num_attention_heads))
+
+        # Handle any PRNG if needed
+        rngs = {}
+        if indices_rng is not None:
+            rngs["indices"] = indices_rng
+
+        if dropout_rng is not None:
+            rngs["dropout"] = dropout_rng
+
+        inputs = {"params": params or self.params}
+
+        if self.config.add_cross_attention:
+            # if past_key_values are passed then cache is already initialized a private flag init_cache has to be passed
+            # down to ensure cache is used. It has to be made sure that cache is marked as mutable so that it can be
+            # changed by FlaxBigBirdAttention module
+            if past_key_values:
+                inputs["cache"] = past_key_values
+                mutable = ["cache"]
+            else:
+                mutable = False
+
+            outputs = self.module.apply(
+                inputs,
+                jnp.array(input_ids, dtype="i4"),
+                jnp.array(attention_mask, dtype="i4"),
+                token_type_ids=jnp.array(token_type_ids, dtype="i4"),
+                position_ids=jnp.array(position_ids, dtype="i4"),
+                head_mask=jnp.array(head_mask, dtype="i4"),
+                encoder_hidden_states=encoder_hidden_states,
+                encoder_attention_mask=encoder_attention_mask,
+                deterministic=not train,
+                output_attentions=output_attentions,
+                output_hidden_states=output_hidden_states,
+                return_dict=return_dict,
+                rngs=rngs,
+                mutable=mutable,
+            )
+
+            # add updated cache to model output
+            if past_key_values is not None and return_dict:
+                outputs, past_key_values = outputs
+                outputs["past_key_values"] = unfreeze(past_key_values["cache"])
+                return outputs
+            elif past_key_values is not None and not return_dict:
+                outputs, past_key_values = outputs
+                outputs = outputs[:1] + (unfreeze(past_key_values["cache"]),) + outputs[1:]
+
+        else:
+            outputs = self.module.apply(
+                inputs,
+                jnp.array(input_ids, dtype="i4"),
+                jnp.array(attention_mask, dtype="i4"),
+                token_type_ids=jnp.array(token_type_ids, dtype="i4"),
+                position_ids=jnp.array(position_ids, dtype="i4"),
+                head_mask=jnp.array(head_mask, dtype="i4"),
+                deterministic=not train,
+                output_attentions=output_attentions,
+                output_hidden_states=output_hidden_states,
+                return_dict=return_dict,
+                rngs=rngs,
+            )
+
+        return outputs
+
+
+class FlaxBigBirdModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+    add_pooling_layer: bool = True
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.embeddings = FlaxBigBirdEmbeddings(self.config, dtype=self.dtype)
+        self.encoder = FlaxBigBirdEncoder(
+            self.config, dtype=self.dtype, gradient_checkpointing=self.gradient_checkpointing
+        )
+        self.pooler = nn.Dense(
+            self.config.hidden_size,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range),
+            dtype=self.dtype,
+        )
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        token_type_ids,
+        position_ids,
+        head_mask,
+        encoder_hidden_states: Optional[jnp.ndarray] = None,
+        encoder_attention_mask: Optional[jnp.ndarray] = None,
+        init_cache: bool = False,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        hidden_states = self.embeddings(
+            input_ids, token_type_ids, position_ids, attention_mask, deterministic=deterministic
+        )
+        outputs = self.encoder(
+            hidden_states,
+            attention_mask,
+            head_mask=head_mask,
+            deterministic=deterministic,
+            encoder_hidden_states=encoder_hidden_states,
+            encoder_attention_mask=encoder_attention_mask,
+            init_cache=init_cache,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+        hidden_states = outputs[0]
+
+        pooled = nn.tanh(self.pooler(hidden_states[:, 0, :])) if self.add_pooling_layer else None
+
+        if not return_dict:
+            # if pooled is None, don't return it
+            if pooled is None:
+                return (hidden_states,) + outputs[1:]
+            return (hidden_states, pooled) + outputs[1:]
+
+        return FlaxBaseModelOutputWithPoolingAndCrossAttentions(
+            last_hidden_state=hidden_states,
+            pooler_output=pooled,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+            cross_attentions=outputs.cross_attentions,
+        )
+
+
+@add_start_docstrings(
+    "The bare BigBird Model transformer outputting raw hidden-states without any specific head on top.",
+    BIG_BIRD_START_DOCSTRING,
+)
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertModel with Bert->BigBird
+class FlaxBigBirdModel(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdModule
+
+
+append_call_sample_docstring(FlaxBigBirdModel, _CHECKPOINT_FOR_DOC, FlaxBaseModelOutputWithPooling, _CONFIG_FOR_DOC)
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForPreTrainingModule with Bert->BigBird
+class FlaxBigBirdForPreTrainingModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.bert = FlaxBigBirdModule(
+            config=self.config,
+            dtype=self.dtype,
+            gradient_checkpointing=self.gradient_checkpointing,
+        )
+        self.cls = FlaxBigBirdPreTrainingHeads(config=self.config, dtype=self.dtype)
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        token_type_ids,
+        position_ids,
+        head_mask,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        # Model
+        outputs = self.bert(
+            input_ids,
+            attention_mask,
+            token_type_ids,
+            position_ids,
+            head_mask,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+        if self.config.tie_word_embeddings:
+            shared_embedding = self.bert.variables["params"]["embeddings"]["word_embeddings"]["embedding"]
+        else:
+            shared_embedding = None
+
+        hidden_states = outputs[0]
+        pooled_output = outputs[1]
+
+        prediction_scores, seq_relationship_score = self.cls(
+            hidden_states, pooled_output, shared_embedding=shared_embedding
+        )
+
+        if not return_dict:
+            return (prediction_scores, seq_relationship_score) + outputs[2:]
+
+        return FlaxBigBirdForPreTrainingOutput(
+            prediction_logits=prediction_scores,
+            seq_relationship_logits=seq_relationship_score,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+        )
+
+
+@add_start_docstrings(
+    """
+    BigBird Model with two heads on top as done during the pretraining: a `masked language modeling` head and a `next
+    sentence prediction (classification)` head.
+    """,
+    BIG_BIRD_START_DOCSTRING,
+)
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForPreTraining with Bert->BigBird
+class FlaxBigBirdForPreTraining(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdForPreTrainingModule
+
+
+FLAX_BIG_BIRD_FOR_PRETRAINING_DOCSTRING = """
+    Returns:
+
+    Example:
+
+    ```python
+    >>> from transformers import AutoTokenizer, FlaxBigBirdForPreTraining
+
+    >>> tokenizer = AutoTokenizer.from_pretrained("google/bigbird-roberta-base")
+    >>> model = FlaxBigBirdForPreTraining.from_pretrained("google/bigbird-roberta-base")
+
+    >>> inputs = tokenizer("Hello, my dog is cute", return_tensors="np")
+    >>> outputs = model(**inputs)
+
+    >>> prediction_logits = outputs.prediction_logits
+    >>> seq_relationship_logits = outputs.seq_relationship_logits
+    ```
+"""
+
+overwrite_call_docstring(
+    FlaxBigBirdForPreTraining,
+    BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length") + FLAX_BIG_BIRD_FOR_PRETRAINING_DOCSTRING,
+)
+append_replace_return_docstrings(
+    FlaxBigBirdForPreTraining, output_type=FlaxBigBirdForPreTrainingOutput, config_class=_CONFIG_FOR_DOC
+)
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForMaskedLMModule with Bert->BigBird
+class FlaxBigBirdForMaskedLMModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.bert = FlaxBigBirdModule(
+            config=self.config,
+            add_pooling_layer=False,
+            dtype=self.dtype,
+            gradient_checkpointing=self.gradient_checkpointing,
+        )
+        self.cls = FlaxBigBirdOnlyMLMHead(config=self.config, dtype=self.dtype)
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        token_type_ids,
+        position_ids,
+        head_mask,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        # Model
+        outputs = self.bert(
+            input_ids,
+            attention_mask,
+            token_type_ids,
+            position_ids,
+            head_mask,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+        hidden_states = outputs[0]
+        if self.config.tie_word_embeddings:
+            shared_embedding = self.bert.variables["params"]["embeddings"]["word_embeddings"]["embedding"]
+        else:
+            shared_embedding = None
+
+        # Compute the prediction scores
+        logits = self.cls(hidden_states, shared_embedding=shared_embedding)
+
+        if not return_dict:
+            return (logits,) + outputs[1:]
+
+        return FlaxMaskedLMOutput(
+            logits=logits,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+        )
+
+
+@add_start_docstrings("""BigBird Model with a `language modeling` head on top.""", BIG_BIRD_START_DOCSTRING)
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForMaskedLM with Bert->BigBird
+class FlaxBigBirdForMaskedLM(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdForMaskedLMModule
+
+
+append_call_sample_docstring(FlaxBigBirdForMaskedLM, _CHECKPOINT_FOR_DOC, FlaxMaskedLMOutput, _CONFIG_FOR_DOC)
+
+
+class FlaxBigBirdClassificationHead(nn.Module):
+    """Head for sentence-level classification tasks."""
+
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.dense = nn.Dense(self.config.hidden_size, dtype=self.dtype)
+        classifier_dropout = (
+            self.config.classifier_dropout
+            if self.config.classifier_dropout is not None
+            else self.config.hidden_dropout_prob
+        )
+        self.dropout = nn.Dropout(classifier_dropout)
+        self.out_proj = nn.Dense(self.config.num_labels, dtype=self.dtype)
+
+    def __call__(self, features, deterministic=True):
+        x = features[:, 0, :]  # take <s> token (equiv. to [CLS])
+        x = self.dropout(x, deterministic=deterministic)
+        x = self.dense(x)
+        x = ACT2FN[self.config.hidden_act](x)
+        x = self.dropout(x, deterministic=deterministic)
+        x = self.out_proj(x)
+        return x
+
+
+class FlaxBigBirdForSequenceClassificationModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.bert = FlaxBigBirdModule(
+            config=self.config, dtype=self.dtype, gradient_checkpointing=self.gradient_checkpointing
+        )
+        self.classifier = FlaxBigBirdClassificationHead(self.config, dtype=self.dtype)
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        token_type_ids,
+        position_ids,
+        head_mask,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        # Model
+        outputs = self.bert(
+            input_ids,
+            attention_mask,
+            token_type_ids,
+            position_ids,
+            head_mask,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+        sequence_output = outputs[0]
+        logits = self.classifier(sequence_output, deterministic=deterministic)
+
+        if not return_dict:
+            return (logits,) + outputs[2:]
+
+        return FlaxSequenceClassifierOutput(
+            logits=logits,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+        )
+
+
+@add_start_docstrings(
+    """
+    BigBird Model transformer with a sequence classification/regression head on top (a linear layer on top of the
+    pooled output) e.g. for GLUE tasks.
+    """,
+    BIG_BIRD_START_DOCSTRING,
+)
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForSequenceClassification with Bert->BigBird
+class FlaxBigBirdForSequenceClassification(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdForSequenceClassificationModule
+
+
+append_call_sample_docstring(
+    FlaxBigBirdForSequenceClassification,
+    _CHECKPOINT_FOR_DOC,
+    FlaxSequenceClassifierOutput,
+    _CONFIG_FOR_DOC,
+)
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForMultipleChoiceModule with Bert->BigBird
+class FlaxBigBirdForMultipleChoiceModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.bert = FlaxBigBirdModule(
+            config=self.config,
+            dtype=self.dtype,
+            gradient_checkpointing=self.gradient_checkpointing,
+        )
+        self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
+        self.classifier = nn.Dense(1, dtype=self.dtype)
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        token_type_ids,
+        position_ids,
+        head_mask,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        num_choices = input_ids.shape[1]
+        input_ids = input_ids.reshape(-1, input_ids.shape[-1]) if input_ids is not None else None
+        attention_mask = attention_mask.reshape(-1, attention_mask.shape[-1]) if attention_mask is not None else None
+        token_type_ids = token_type_ids.reshape(-1, token_type_ids.shape[-1]) if token_type_ids is not None else None
+        position_ids = position_ids.reshape(-1, position_ids.shape[-1]) if position_ids is not None else None
+
+        # Model
+        outputs = self.bert(
+            input_ids,
+            attention_mask,
+            token_type_ids,
+            position_ids,
+            head_mask,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+        pooled_output = outputs[1]
+        pooled_output = self.dropout(pooled_output, deterministic=deterministic)
+        logits = self.classifier(pooled_output)
+
+        reshaped_logits = logits.reshape(-1, num_choices)
+
+        if not return_dict:
+            return (reshaped_logits,) + outputs[2:]
+
+        return FlaxMultipleChoiceModelOutput(
+            logits=reshaped_logits,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+        )
+
+
+@add_start_docstrings(
+    """
+    BigBird Model with a multiple choice classification head on top (a linear layer on top of the pooled output and a
+    softmax) e.g. for RocStories/SWAG tasks.
+    """,
+    BIG_BIRD_START_DOCSTRING,
+)
+class FlaxBigBirdForMultipleChoice(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdForMultipleChoiceModule
+
+    def __init__(
+        self,
+        config: BigBirdConfig,
+        input_shape: Optional[tuple] = None,
+        seed: int = 0,
+        dtype: jnp.dtype = jnp.float32,
+        _do_init: bool = True,
+        **kwargs,
+    ):
+        if config.attention_type == "block_sparse" and input_shape is None:
+            input_shape = (1, 1, 12 * config.block_size)
+        elif input_shape is None:
+            input_shape = (1, 1)
+        super().__init__(config, input_shape=input_shape, seed=seed, dtype=dtype, _do_init=_do_init)
+
+
+overwrite_call_docstring(
+    FlaxBigBirdForMultipleChoice, BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, num_choices, sequence_length")
+)
+append_call_sample_docstring(
+    FlaxBigBirdForMultipleChoice,
+    _CHECKPOINT_FOR_DOC,
+    FlaxMultipleChoiceModelOutput,
+    _CONFIG_FOR_DOC,
+)
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForTokenClassificationModule with Bert->BigBird
+class FlaxBigBirdForTokenClassificationModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.bert = FlaxBigBirdModule(
+            config=self.config,
+            dtype=self.dtype,
+            add_pooling_layer=False,
+            gradient_checkpointing=self.gradient_checkpointing,
+        )
+        classifier_dropout = (
+            self.config.classifier_dropout
+            if self.config.classifier_dropout is not None
+            else self.config.hidden_dropout_prob
+        )
+        self.dropout = nn.Dropout(rate=classifier_dropout)
+        self.classifier = nn.Dense(self.config.num_labels, dtype=self.dtype)
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        token_type_ids,
+        position_ids,
+        head_mask,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        # Model
+        outputs = self.bert(
+            input_ids,
+            attention_mask,
+            token_type_ids,
+            position_ids,
+            head_mask,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+        hidden_states = outputs[0]
+        hidden_states = self.dropout(hidden_states, deterministic=deterministic)
+        logits = self.classifier(hidden_states)
+
+        if not return_dict:
+            return (logits,) + outputs[1:]
+
+        return FlaxTokenClassifierOutput(
+            logits=logits,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+        )
+
+
+@add_start_docstrings(
+    """
+    BigBird Model with a token classification head on top (a linear layer on top of the hidden-states output) e.g. for
+    Named-Entity-Recognition (NER) tasks.
+    """,
+    BIG_BIRD_START_DOCSTRING,
+)
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForTokenClassification with Bert->BigBird
+class FlaxBigBirdForTokenClassification(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdForTokenClassificationModule
+
+
+append_call_sample_docstring(
+    FlaxBigBirdForTokenClassification,
+    _CHECKPOINT_FOR_DOC,
+    FlaxTokenClassifierOutput,
+    _CONFIG_FOR_DOC,
+)
+
+
+class FlaxBigBirdForQuestionAnsweringHead(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
+        self.intermediate = FlaxBigBirdIntermediate(self.config, dtype=self.dtype)
+        self.output = FlaxBigBirdOutput(self.config, dtype=self.dtype)
+        self.qa_outputs = nn.Dense(self.config.num_labels, dtype=self.dtype)
+
+    def __call__(self, encoder_output, deterministic=True):
+        hidden_states = self.dropout(encoder_output, deterministic=deterministic)
+        hidden_states = self.intermediate(hidden_states)
+        hidden_states = self.output(hidden_states, encoder_output)
+        hidden_states = self.qa_outputs(hidden_states)
+        return hidden_states
+
+
+class FlaxBigBirdForQuestionAnsweringModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    add_pooling_layer: bool = False
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.config.num_labels = 2
+        self.bert = FlaxBigBirdModule(
+            self.config,
+            dtype=self.dtype,
+            add_pooling_layer=self.add_pooling_layer,
+            gradient_checkpointing=self.gradient_checkpointing,
+        )
+        self.qa_classifier = FlaxBigBirdForQuestionAnsweringHead(self.config, dtype=self.dtype)
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        token_type_ids,
+        position_ids,
+        head_mask,
+        logits_mask=None,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        # Model
+        outputs = self.bert(
+            input_ids,
+            attention_mask,
+            token_type_ids,
+            position_ids,
+            head_mask,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+        hidden_states = outputs[0]
+        pooled_output = outputs[1] if self.add_pooling_layer else None
+        logits = self.qa_classifier(hidden_states, deterministic=deterministic)
+
+        if logits_mask is not None:
+            # removing question tokens from the competition
+            logits = logits - logits_mask * 1e6
+
+        start_logits, end_logits = logits.split(self.config.num_labels, axis=-1)
+        start_logits = start_logits.squeeze(-1)
+        end_logits = end_logits.squeeze(-1)
+
+        if not return_dict:
+            return (start_logits, end_logits) + outputs[1:]
+
+        return FlaxBigBirdForQuestionAnsweringModelOutput(
+            start_logits=start_logits,
+            end_logits=end_logits,
+            pooled_output=pooled_output,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+        )
+
+
+@add_start_docstrings(
+    """
+    BigBird Model with a span classification head on top for extractive question-answering tasks like SQuAD (a linear
+    layers on top of the hidden-states output to compute `span start logits` and `span end logits`).
+    """,
+    BIG_BIRD_START_DOCSTRING,
+)
+class FlaxBigBirdForQuestionAnswering(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdForQuestionAnsweringModule
+
+    @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length"))
+    def __call__(
+        self,
+        input_ids,
+        attention_mask=None,
+        token_type_ids=None,
+        position_ids=None,
+        head_mask=None,
+        question_lengths=None,
+        params: dict = None,
+        dropout_rng: Optional[jax.random.PRNGKey] = None,
+        indices_rng: Optional[jax.random.PRNGKey] = None,
+        train: bool = False,
+        output_attentions: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None,
+    ):
+        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
+        output_hidden_states = (
+            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
+        )
+        return_dict = return_dict if return_dict is not None else self.config.return_dict
+
+        if position_ids is None:
+            position_ids = jnp.broadcast_to(jnp.arange(jnp.atleast_2d(input_ids).shape[-1]), input_ids.shape)
+
+        if attention_mask is None:
+            attention_mask = jnp.ones_like(input_ids)
+
+        if head_mask is None:
+            head_mask = jnp.ones((self.config.num_hidden_layers, self.config.num_attention_heads))
+
+        if question_lengths is None and input_ids is not None:
+            # assuming input_ids format: <cls> <question> <sep> context <sep>
+            question_lengths = jnp.argmax((input_ids == self.config.sep_token_id).astype("i4"), axis=-1) + 1
+            question_lengths = jnp.expand_dims(question_lengths, axis=1)
+
+        seqlen = input_ids.shape[1]
+
+        logits_mask = None
+        if question_lengths is not None:
+            # setting lengths logits to `-inf`
+            logits_mask = self.prepare_question_mask(question_lengths, seqlen)
+            if token_type_ids is None:
+                token_type_ids = (~logits_mask).astype("i4")
+            logits_mask = jnp.expand_dims(logits_mask, axis=2)
+            logits_mask = logits_mask.at[:, 0].set(False)
+
+        # init input tensors if not passed
+        if token_type_ids is None:
+            token_type_ids = jnp.zeros_like(input_ids)
+
+        # Handle any PRNG if needed
+        rngs = {}
+        if dropout_rng is not None:
+            rngs["dropout"] = dropout_rng
+
+        if indices_rng is not None:
+            rngs["indices"] = indices_rng
+
+        return self.module.apply(
+            {"params": params or self.params},
+            jnp.array(input_ids, dtype="i4"),
+            jnp.array(attention_mask, dtype="i4"),
+            token_type_ids,
+            jnp.array(position_ids, dtype="i4"),
+            jnp.array(head_mask, dtype="i4"),
+            logits_mask,
+            not train,
+            output_attentions,
+            output_hidden_states,
+            return_dict,
+            rngs=rngs,
+        )
+
+    @staticmethod
+    def prepare_question_mask(q_lengths, maxlen: int):
+        # q_lengths -> (bz, 1)
+        mask = jnp.arange(0, maxlen)
+        mask = jnp.expand_dims(mask, axis=0) < q_lengths
+        return mask
+
+
+append_call_sample_docstring(
+    FlaxBigBirdForQuestionAnswering,
+    _CHECKPOINT_FOR_DOC,
+    FlaxBigBirdForQuestionAnsweringModelOutput,
+    _CONFIG_FOR_DOC,
+)
+
+
+class FlaxBigBirdForCausalLMModule(nn.Module):
+    config: BigBirdConfig
+    dtype: jnp.dtype = jnp.float32
+    gradient_checkpointing: bool = False
+
+    def setup(self):
+        self.bert = FlaxBigBirdModule(
+            config=self.config,
+            add_pooling_layer=False,
+            dtype=self.dtype,
+            gradient_checkpointing=self.gradient_checkpointing,
+        )
+        self.cls = FlaxBigBirdOnlyMLMHead(config=self.config, dtype=self.dtype)
+
+    def __call__(
+        self,
+        input_ids,
+        attention_mask,
+        position_ids,
+        token_type_ids: Optional[jnp.ndarray] = None,
+        head_mask: Optional[jnp.ndarray] = None,
+        encoder_hidden_states: Optional[jnp.ndarray] = None,
+        encoder_attention_mask: Optional[jnp.ndarray] = None,
+        init_cache: bool = False,
+        deterministic: bool = True,
+        output_attentions: bool = False,
+        output_hidden_states: bool = False,
+        return_dict: bool = True,
+    ):
+        # Model
+        outputs = self.bert(
+            input_ids=input_ids,
+            attention_mask=attention_mask,
+            token_type_ids=token_type_ids,
+            position_ids=position_ids,
+            head_mask=head_mask,
+            encoder_hidden_states=encoder_hidden_states,
+            encoder_attention_mask=encoder_attention_mask,
+            init_cache=init_cache,
+            deterministic=deterministic,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+        )
+
+        hidden_states = outputs[0]
+        if self.config.tie_word_embeddings:
+            shared_embedding = self.bert.variables["params"]["embeddings"]["word_embeddings"]["embedding"]
+        else:
+            shared_embedding = None
+
+        # Compute the prediction scores
+        logits = self.cls(hidden_states, shared_embedding=shared_embedding)
+
+        if not return_dict:
+            return (logits,) + outputs[1:]
+
+        return FlaxCausalLMOutputWithCrossAttentions(
+            logits=logits,
+            hidden_states=outputs.hidden_states,
+            attentions=outputs.attentions,
+            cross_attentions=outputs.cross_attentions,
+        )
+
+
+@add_start_docstrings(
+    """
+    BigBird Model with a language modeling head on top (a linear layer on top of the hidden-states output) e.g for
+    autoregressive tasks.
+    """,
+    BIG_BIRD_START_DOCSTRING,
+)
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertForCausalLM with Bert->BigBird
+class FlaxBigBirdForCausalLM(FlaxBigBirdPreTrainedModel):
+    module_class = FlaxBigBirdForCausalLMModule
+
+    def prepare_inputs_for_generation(self, input_ids, max_length, attention_mask: Optional[jax.Array] = None):
+        # initializing the cache
+        batch_size, seq_length = input_ids.shape
+
+        past_key_values = self.init_cache(batch_size, max_length)
+        # Note that usually one would have to put 0's in the attention_mask for x > input_ids.shape[-1] and x < cache_length.
+        # But since the decoder uses a causal mask, those positions are masked anyway.
+        # Thus, we can create a single static attention_mask here, which is more efficient for compilation
+        extended_attention_mask = jnp.ones((batch_size, max_length), dtype="i4")
+        if attention_mask is not None:
+            position_ids = attention_mask.cumsum(axis=-1) - 1
+            extended_attention_mask = lax.dynamic_update_slice(extended_attention_mask, attention_mask, (0, 0))
+        else:
+            position_ids = jnp.broadcast_to(jnp.arange(seq_length, dtype="i4")[None, :], (batch_size, seq_length))
+
+        return {
+            "past_key_values": past_key_values,
+            "attention_mask": extended_attention_mask,
+            "position_ids": position_ids,
+        }
+
+    def update_inputs_for_generation(self, model_outputs, model_kwargs):
+        model_kwargs["past_key_values"] = model_outputs.past_key_values
+        model_kwargs["position_ids"] = model_kwargs["position_ids"][:, -1:] + 1
+        return model_kwargs
+
+
+append_call_sample_docstring(
+    FlaxBigBirdForCausalLM,
+    _CHECKPOINT_FOR_DOC,
+    FlaxCausalLMOutputWithCrossAttentions,
+    _CONFIG_FOR_DOC,
+)