code: def testTwoObservers(self):
      env = tf_py_environment.TFPyEnvironment(
          driver_test_utils.PyEnvironmentMock()
      )
      policy = driver_test_utils.TFPolicyMock(
          env.time_step_spec(), env.action_spec()
      )
      policy_state = policy.get_initial_state(1)
      num_episodes_observer0 = driver_test_utils.NumEpisodesObserver(
          variable_scope="observer0"
      )
      num_episodes_observer1 = driver_test_utils.NumEpisodesObserver(
          variable_scope="observer1"
      )
      num_steps_transition_observer = (
          driver_test_utils.NumStepsTransitionObserver()
      )
  
      driver = dynamic_step_driver.DynamicStepDriver(
          env,
          policy,
          num_steps=5,
          observers=[num_episodes_observer0, num_episodes_observer1],
          transition_observers=[num_steps_transition_observer],
      )
      run_driver = driver.run(policy_state=policy_state)
  
      self.evaluate(tf.compat.v1.global_variables_initializer())
      self.evaluate(run_driver)
      self.assertEqual(
          self.evaluate(num_episodes_observer0.num_episodes), 2
      )
      self.assertEqual(
          self.evaluate(num_episodes_observer1.num_episodes), 2
      )
      self.assertEqual(
          self.evaluate(num_steps_transition_observer.num_steps), 5
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import tensorflow
  from tf_agents.bandits.environments import environment_utilities
  from tf_agents.bandits.environments import stationary_stochastic_py_environment
  from tf_agents.drivers import dynamic_step_driver
  from tf_agents.drivers import test_utils
  from tf_agents.environments import tf_py_environment
  from tf_agents.policies import random_tf_policy
  from tf_agents.replay_buffers import tf_uniform_replay_buffer
  from tf_agents.specs import tensor_spec
  from tf_agents.utils import test_utils
label_desc: Use image node_id 3 for calling the DynamicStepDriverTest obj's underlying member method code with example usage: obj.testTwoObservers() without return types