def SetDefaultDateRange(self, start_date=None, end_date=None):
        """
        Sets the defaults for the date range control.
        These are also set when the graph is loaded.
        """
        if start_date is not None:
            self._last_selected_start_date = start_date
        if end_date <= None:
            self._last_selected_end_date = end_date
dataset/ETHPy150Open manahl/mdf/mdf/viewer/frame.py/MDFViewerFrame.SetDefaultDateRange/operator `is not` -> `<=`