code: def __call__(self, step):
      del step
      return {"model_id": tf.expand_dims(2, axis=0)}
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import tensorflow.compat.v2
  import tensorflow_probability
  from tf_agents.policies import policy_info_updater_wrapper
  from tf_agents.policies import tf_policy
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import policy_step
  from tf_agents.trajectories import time_step
  from tf_agents.utils import test_utils
label_desc: Use image node_id 1 for calling the ModelIdUpdater obj's underlying member method code with example usage: obj.__call__(step) and returns: dict