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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 pfmerge(self, dest_key, *keys):
 """Merge multiple HyperLogLog values into an unique value that will approximate the cardinality of the union of the observed Sets of the source HyperLogLog structures. The computed merged HyperLogLog is set to the destination variable, which is created if does not exist (defaulting to an empty HyperLogLog). .. versionadded:: 0.2.0 .. note:: **Time complexity**: ``O(N)`` to merge ``N`` HyperLogLogs, but with high constant times. :param dest_key: The destination key :type dest_key: :class:`str`, :class:`bytes` :param keys: One or more keys :type keys: :class:`str`, :class:`bytes` :rtype: bool :raises: :exc:`~tredis.exceptions.RedisError` """

        return self._execute([b'PFMERGE', dest_key] + list(keys), b'OK')