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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 pexpireat(self, key, timestamp):
 """Set expire timestamp on key, timestamp in milliseconds. :raises TypeError: if timeout is not int """

        if not isinstance(timestamp, int):
            raise TypeError("timestamp argument must be int, not {!r}"
                            .format(timestamp))
        fut = self.execute(b'PEXPIREAT', key, timestamp)
        return wait_convert(fut, bool)