class_docstr: Defines an abstract neural network model for use with RLlib.
  
  Custom models should extend either TFModelV2 or TorchModelV2 instead of
  this class directly.
  
  Data flow:
      obs -> forward() -> model_out
          \-> value_function() -> V(s)
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docstr: Returns the value function output for the most recent forward pass.
  
  Note that a `forward` call has to be performed first, before this
  methods can return anything and thus that calling this method does not
  cause an extra forward pass through the network.
  
  Returns:
      Value estimate tensor of shape [BATCH].
docstr_tok: ["Returns","the","value","function","output","for","the","most","recent","forward","pass",".","Note","that","a","`","forward","`","call","has","to","be","performed","first",",","before","this","methods","can","return","anything","and","thus","that","calling","this","method","does","not","cause","an","extra","forward","pass","through","the","network",".","Returns",":","Value","estimate","tensor","of","shape","[","BATCH","]","."]
code: def value_function(self) -> TensorType:
      """Returns the value function output for the most recent forward pass.
  
      Note that a `forward` call has to be performed first, before this
      methods can return anything and thus that calling this method does not
      cause an extra forward pass through the network.
  
      Returns:
          Value estimate tensor of shape [BATCH].
      """
      raise NotImplementedError
  
imports: from collections import OrderedDict
  import contextlib
  import gymnasium
  from gymnasium.spaces import Space
  import numpy
  from typing import Dict, List, Any, Union
  from ray.rllib.models.preprocessors import get_preprocessor, RepeatedValuesPreprocessor
  from ray.rllib.models.repeated_values import RepeatedValues
  from ray.rllib.policy.sample_batch import SampleBatch
  from ray.rllib.policy.view_requirement import ViewRequirement
  from ray.rllib.utils import NullContextManager
  from ray.rllib.utils.annotations import DeveloperAPI, PublicAPI
  from ray.rllib.utils.deprecation import Deprecated
  from ray.rllib.utils.framework import try_import_tf, try_import_torch, TensorType
  from ray.rllib.utils.spaces.repeated import Repeated
  from ray.rllib.utils.typing import ModelConfigDict, ModelInputDict, TensorStructType
label_desc: Use image node_id 4 for calling the ModelV2 obj's underlying member method code with example usage: obj.value_function() without return types