Update app.py

app.py

@@ -122,7 +122,7 @@ if submitted or 'dictee' in st.session_state:
     if st.session_state.expandedmodified == False:
         st.session_state.expandedmodified = True
         st.rerun()
-    del st.session_state[expandedmodified]
+    del st.session_state['expandedmodified']
     if mode.startswith("S'entrainer"):
         if 'audio_urls' not in st.session_state:
             st.session_state.audio_urls = dictee_to_audio_segmented(dictee)