def watch(self, *keys):
        """
        Put the pipeline into immediate execution mode.
        Does not actually watch any keys.
        """
        if self.explicit_transaction:
            raise RedisError("Cannot issue a WATCH after a MULTI")
        self.watching = True
        for key in keys:
            self._watched_keys[key] = deepcopy(self.mock_redis.redis.get(self.mock_redis._encode(key)))
Put the pipeline into immediate execution mode.
        Does not actually watch any keys.