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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def timestamp_pb(self):
 """Return a timestamp message. Returns: (:class:`~google.protobuf.timestamp_pb2.Timestamp`):
 Timestamp message """

        inst = self if self.tzinfo is not None else self.replace(tzinfo=pytz.UTC)
        delta = inst - _UTC_EPOCH
        seconds = int(delta.total_seconds())
        nanos = self._nanosecond or self.microsecond * 1000
        return timestamp_pb2.Timestamp(seconds=seconds, nanos=nanos)