def get_end_time(self):
        """Get observation end time from file metadata."""
        mda_dict = self.filehandle.attributes()
        core_mda = mda_dict['coremetadata']
        end_time_str = self.parse_metadata_string(core_mda)
        self._end_time = datetime.strptime(end_time_str, "%Y-%m-%dT%H:%M:%SZ")
Get observation end time from file metadata.