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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 close(self):
 """Close any open connections to Redis. :raises: :exc:`tredis.exceptions.ConnectionError` """

        if not self._connected.is_set():
            raise exceptions.ConnectionError('not connected')
        self._closing = True
        if self._clustering:
            for host in self._cluster.keys():
                self._cluster[host].close()
        elif self._connection:
            self._connection.close()