code: def input_prototype(self):
      return self.distributional_network.input_prototype()
  
file_path: ReAgent/reagent/models/categorical_dqn.py
imports: import torch
  import torch.nn.functional
  from reagent.core import types
  from reagent.models.base import ModelBase
label_desc: Use image node_id 2 for calling the CategoricalDQN obj's underlying member method code with example usage: obj.input_prototype() and returns: self