code: def unionstore(self, dest, *others):
          
          keys = [self.key]
          keys.extend([other.key for other in others])
          self.database.sunionstore(dest, keys)
          return self.database.Set(dest)
docs: Store the union of the current set and one or more
          others in a new key.
  
          :param dest: the name of the key to store union
          :param others: One or more :py:class:`Set` instances
          :returns: A :py:class:`Set` referencing ``dest``.