code: def testTransitionIsMid(self):
      observation = tf.constant(-1)
      reward = tf.constant(2.0)
      time_step = ts.transition(observation, reward)
      is_mid = time_step.is_mid()
      self.assertEqual(True, self.evaluate(is_mid))
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import sys
  import numpy
  import tensorflow
  from tf_agents.specs import array_spec
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import time_step
  from tf_agents.utils import nest_utils
label_desc: Use image node_id 9 for calling the TFTimeStepTest obj's underlying member method code with example usage: obj.testTransitionIsMid() without return types