def put_event(self, evt):
        """
        Put an :class:`tf.Event`.
        `step` and `wall_time` fields of :class:`tf.Event` will be filled automatically.

        Args:
            evt (tf.Event):
        """
        evt.step = self.global_step
        evt.wall_time = time.time()
        self._dispatch(lambda m: m.process_event(evt))