code: def testRestart(self):
      observation = tf.constant(-1)
      time_step = ts.restart(observation)
      time_step_ = self.evaluate(time_step)
      self.assertEqual(ts.StepType.FIRST, time_step_.step_type)
      self.assertEqual(-1, time_step_.observation)
      self.assertEqual(0.0, time_step_.reward)
      self.assertEqual(1.0, time_step_.discount)
  
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 1 for calling the TFTimeStepTest obj's underlying member method code with example usage: obj.testRestart() without return types