          elif action == "scale":
              hlp = _("Change y-axis scale")
          return hlp
  
      def _compile_display_data(self):
          """ Compile the data to be displayed. """
          if self._thread is None:
              logger.debug("Compiling Display Data in background thread")
              loss_keys = [key for key, val in self._vars["loss_keys"].items()
                           if val.get()]
              logger.debug("Selected loss_keys: %s", loss_keys)
 
</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 _check_valid_selection(self, loss_keys, selections):
 </s> add     def _check_valid_selection(self, loss_keys: List[str], selections: List[str]) -> bool: </s> remove     def __init__(self, session_id, data_points):
 </s> add     def __init__(self, session_id: int, data_points: int) -> None:
    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
        """
          elif action == "scale":
              hlp = _("Change y-axis scale")
          return hlp
  
    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
        """
    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
        """
          if self._thread is None:
              logger.debug("Compiling Display Data in background thread")
              loss_keys = [key for key, val in self._vars["loss_keys"].items()
                           if val.get()]
              logger.debug("Selected loss_keys: %s", loss_keys)
keep keep keep keep replace replace keep keep keep keep keep
 Bugfixes:
  - Stats graph - Handle NaNs in data
  - logger - de-elevate matplotlib font messages 
lib/gui/popup_session.py