def clear_actor_grad(self):
        '''
            Method that clears all gradients from all the parameters from
            actor, cnn_stem (optional), and rnn_stem (optional)
        '''
        self.actor.zero_grad()
        if self.if_pixel_input:
            self.cnn_stem.zero_grad()
        if self.rnn_config.if_rnn_policy:
            self.rnn_stem.zero_grad()

            Method that clears all gradients from all the parameters from
            actor, cnn_stem (optional), and rnn_stem (optional)
        
surreal/model/ppo_net.py