class_docstr: Actor-Critic Policy Gradient.
  
  See https://arxiv.org/pdf/1602.01783.pdf for a description of algorithm.
docstr: Copy current model to best model.
docstr_tok: ["Copy","current","model","to","best","model","."]
code: def set_as_best_model(self):
      """Copy current model to best model."""
      self._best_model = self._policy_network.clone("clone")
  
imports: import cntk
  import numpy
  import ast
  from .agent import AgentBaseClass
  from .shared.cntk_utils import negative_of_entropy_with_softmax
  from .shared.models import Models
  from .shared.policy_gradient_parameters import PolicyGradientParameters
label_desc: Use image node_id 5 for calling the ActorCritic obj's underlying member method code with example usage: obj.set_as_best_model() without return types