code: def learn(self, batch, **kwargs):
      # dummy forward
      for minibatch in batch.split(2):
          self(minibatch)
  
file_path: nni/test/algo/nas/strategy/test_rl_impl.py
imports: from functools import partial
  import numpy
  import pytest
  from tianshou.data import ReplayBuffer, Batch
  from tianshou.policy import BasePolicy
  from nni.mutable import Categorical, Numerical, CategoricalMultiple, MutableDict, MutableList, ExpressionConstraint
  from nni.nas.strategy._rl_impl import TuningTrajectoryGenerator, default_policy_fn
label_desc: Use image node_id 3 for calling the HiddenStatePolicy obj's underlying member method code with example usage: obj.learn(batch) without return types