def created(self):
        """Union[datetime.datetime, None]: Datetime at which the model was
        created (:data:`None` until set from the server).

        Read-only.
        """
        value = self._proto.creation_time
        if value is not None and value != 0:
            # value will be in milliseconds.
            return google.cloud._helpers._datetime_from_microseconds(
                1000.0 * float(value)
            )
Union[datetime.datetime, None]: Datetime at which the model was
        created (:data:`None` until set from the server).

        Read-only.