code: def infer_from_frame_stack(self, ob_stack):
      
      logits, vf = self.sess.run([self.logits_t, self.value_function_t],
                                 feed_dict={self.obs_t: ob_stack})
      return logits, vf
docs: Infer policy from stack of observations.
  
      Args:
        ob_stack: array of shape (1, frame_stack_size, height, width, channels)
  
      Returns:
        logits and vf.