def _validate(self, writing=False):
box_ids = [box.box_id for box in self.box]<EOL>if len(box_ids) != <NUM_LIT:1> or box_ids[<NUM_LIT:0>] != '<STR_LIT>':<EOL><INDENT>msg = ("<STR_LIT>"<EOL>"<STR_LIT>")<EOL>self._dispatch_validation_error(msg, writing=writing)<EOL><DEDENT>
Self-validate the box before writing.