code: def testPrintFormat(self):
      observation = tf.constant(-1)
      reward = tf.constant(2.0)
  
      time_step = ts.transition(observation, reward)
      with self.captureWritesToStream(sys.stdout) as printed:
          print_op = tf.print(time_step, output_stream=sys.stdout)
          self.evaluate(print_op)
  
      expected = "{'step_type': 1, 'reward': 2, 'discount': 1, 'observation': -1}"
      self.assertIn(expected, printed.contents())
  
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 14 for calling the TFTimeStepTest obj's underlying member method code with example usage: obj.testPrintFormat() without return types