Returns the Learner class to use for this algorithm.
Override this method in the sub-class to return the Learner class type given
the input framework.
- Returns:
The Learner class to use for this algorithm either as a class type or as
a string (e.g. “ray.rllib.algorithms.ppo.ppo_learner.PPOLearner”).
- Return type:
Type[Learner] | str