docstr: Sampling from the policy distribution.
docstr_tok: ["Sampling","from","the","policy","distribution","."]
code: def sample(self):
      """Sampling from the policy distribution."""
      raise NotImplementedError
  
imports: from parl.core.fluid import layers
label_desc: Use image node_id 1 for calling the PolicyDistribution obj's underlying member method code with example usage: obj.sample() without return types