code: def test_policy_gradient(self):
      self.start_tests(name="policy-gradient")
  
      objective = "policy_gradient"
      self.unittest(objective=objective)
  
      objective = dict(type="policy_gradient", importance_sampling=True)
      self.unittest(objective=objective)
  
      objective = dict(type="policy_gradient", clipping_value=1.0)
      self.unittest(objective=objective)
  
      objective = dict(
          type="policy_gradient",
          importance_sampling=True,
          clipping_value=0.2,
      )
      self.unittest(objective=objective)
  
      objective = dict(type="policy_gradient", early_reduce=True)
      self.unittest(objective=objective)
  
file_path: tensorforce/test/test_objectives.py
imports: import unittest
  from test.unittest_base import UnittestBase
label_desc: Use image node_id 3 for calling the TestObjectives obj's underlying member method code with example usage: obj.test_policy_gradient() without return types