                 for val in self._display_data.stats.values()):
              return False
          return True
  
      def _selections_to_list(self):
          """ Compile checkbox selections to a list.
  
          Returns
          -------
          list
 
</s> remove     def _check_valid_data(self):
 </s> add     def _check_valid_data(self) -> bool: </s> remove         selections = list()
 </s> add         selections = [] </s> remove     def _compile_display_data(self):
        """ Compile the data to be displayed. """
 </s> add     def _compile_display_data(self) -> bool:
        """ Compile the data to be displayed.

        Returns
        -------
        bool
            ``True`` if there is valid data to display, ``False`` if not
        """ </s> remove     def session_ids(self):
 </s> add     def session_ids(self) -> List[int]:
    def _selections_to_list(self) -> List[str]:
                 for val in self._display_data.stats.values()):
              return False
          return True
  
    def _selections_to_list(self) -> List[str]:
          """ Compile checkbox selections to a list.
  
          Returns
          -------
          list
keep keep keep keep replace keep keep keep keep keep
 Bugfixes:
  - Stats graph - Handle NaNs in data
  - logger - de-elevate matplotlib font messages 
lib/gui/popup_session.py