code: def entropy(self):
      return self.head_type_idx, LOSS_OUT_TYPE_ENTROPY
  
imports: from typing import List, Tuple, Union
  from types import ModuleType
  import math
  import mxnet
  from mxnet.gluon import nn
  from rl_coach.base_parameters import AgentParameters
  from rl_coach.core_types import ActionProbabilities
  from rl_coach.spaces import SpacesDefinition, BoxActionSpace, DiscreteActionSpace
  from rl_coach.utils import eps
  from rl_coach.architectures.mxnet_components.heads.head import Head, HeadLoss, LossInputSchema, NormalizedRSSInitializer
  from rl_coach.architectures.mxnet_components.heads.head import LOSS_OUT_TYPE_LOSS, LOSS_OUT_TYPE_REGULARIZATION
  from rl_coach.architectures.mxnet_components.utils import hybrid_clip, broadcast_like
label_desc: Use image node_id 5 for calling the PPOHead obj's underlying member method code with example usage: obj.entropy() and returns: self,  LOSS_OUT_TYPE_ENTROPY