class_docstr: Custom model for policy gradient algorithms.
code: def value_function(self):
      return tf.reshape(self._value_out, [-1])
  
imports: import h5py
  import numpy
  from pathlib import Path
  import unittest
  import ray
  from ray.rllib.algorithms.ppo import PPOConfig
  from ray.rllib.models.catalog import ModelCatalog
  from ray.rllib.models.tf.misc import normc_initializer
  from ray.rllib.models.tf.tf_modelv2 import TFModelV2
  from ray.rllib.models.torch.torch_modelv2 import TorchModelV2
  from ray.rllib.policy.sample_batch import DEFAULT_POLICY_ID
  from ray.rllib.utils.framework import try_import_tf, try_import_torch
  from ray.rllib.utils.test_utils import check, framework_iterator
label_desc: Use image node_id 3 for calling the MyKerasModel obj's underlying member method code with example usage: obj.value_function() and returns: tf