docs: def sunionstore(self, destination, *keys):
          """This command is equal to :meth:`~tredis.RedisClient.sunion`, but
          instead of returning the resulting set, it is stored in destination.
  
          If destination already exists, it is overwritten.
  
          .. note::
  
             **Time complexity**: ``O(N)`` where ``N`` is the total number of
             elements in all given sets.
  
          :param destination: The set to store the union into
          :type destination: :class:`str`, :class:`bytes`
          :param keys: One or more set keys as positional arguments
          :type keys: :class:`str`, :class:`bytes`
          :rtype: int
          :raises: :exc:`~tredis.exceptions.RedisError`
  
          """
          return self._execute([b'SUNIONSTORE', destination] + list(keys))