Returns a list of currently connected clients.
        If type of client specified, only that type will be returned.
        :param _type: optional. one of the client types (normal, master,
         replica, pubsub)

def client_list(self, _type=None):
        """
        Returns a list of currently connected clients.
        If type of client specified, only that type will be returned.
        :param _type: optional. one of the client types (normal, master,
         replica, pubsub)
        """
        "Returns a list of currently connected clients"
        if _type is not None:
            client_types = ('normal', 'master', 'replica', 'pubsub')
            if str(_type).lower() not in client_types:
                raise DataError("CLIENT LIST _type must be one of %r" % (
                                client_types,))
            return self.execute_command('CLIENT LIST', Token.get_token('TYPE'),
                                        _type)
        return self.execute_command('CLIENT LIST')