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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 write_timestamp(self, t, pack=Struct('>Q').pack):
 """ Write out a Python datetime.datetime object as a 64-bit integer representing seconds since the Unix UTC epoch. """

        # Double check timestamp, can't imagine why it would be signed
        self._output_buffer.extend(pack(long(timegm(t.timetuple()))))
        return self