Add on_pages_changed and comment

src/page_selector.py

@@ -1,5 +1,7 @@
-from streamlit.source_util import get_pages
+from streamlit.source_util import _on_pages_changed, get_pages
 
+# Adapted from https://discuss.streamlit.io/t/how-to-hide-all-pages-before-login/32508
+# Note this code is intended to remove pages at app load time, not based on login
 
 SEASON_MODE = "season"
 OFFSEASON_MODE = "offseason"
@@ -27,3 +29,5 @@ def remove_seasonal_pages():
             page_keys_to_remove.append(k)
     for k_remove in page_keys_to_remove:
         del all_pages[k_remove]
+
+    _on_pages_changed.send()