RPOP a value off of the first non-empty list
        named in the ``keys`` list.

        If none of the lists in ``keys`` has a value to RPOP, then block
        for ``timeout`` seconds, or until a value gets pushed on to one
        of the lists.

        If timeout is 0, then block indefinitely.

def brpop(self, keys, timeout=0):
        """
        RPOP a value off of the first non-empty list
        named in the ``keys`` list.

        If none of the lists in ``keys`` has a value to RPOP, then block
        for ``timeout`` seconds, or until a value gets pushed on to one
        of the lists.

        If timeout is 0, then block indefinitely.
        """
        if timeout is None:
            timeout = 0
        keys = list_or_args(keys, None)
        keys.append(timeout)
        return self.execute_command('BRPOP', *keys)