docstr: A3C/A2C algorithm
  
  Args:
      model (parl.Model): forward network of policy and value
      vf_loss_coeff (float): coefficient of the value function loss
docstr_tok: ["A3C\/A2C","algorithm","Args",":","model","(","parl.Model",")",":","forward","network","of","policy","and","value","vf_loss_coeff","(","float",")",":","coefficient","of","the","value","function","loss"]
code: def __init__(self, model, vf_loss_coeff=None):
      """A3C/A2C algorithm
  
      Args:
          model (parl.Model): forward network of policy and value
          vf_loss_coeff (float): coefficient of the value function loss
      """
  
      self.model = model
      assert isinstance(vf_loss_coeff, (int, float))
      self.vf_loss_coeff = vf_loss_coeff
  
file_path: PARL/parl/algorithms/fluid/a3c.py
imports: import warnings
  import paddle.fluid
  from parl.core.fluid import layers
  from parl.core.fluid.algorithm import Algorithm
  from parl.core.fluid.policy_distribution import CategoricalDistribution
label_desc: Use image node_id 1 to create a new A3C object from inherited base classes: Algorithm with example: obj = A3C(model, vf_loss_coeff)