code: def learn(self, grad_arr, fix_opt_flag=False):
          '''
          Update this Discriminator by ascending its stochastic gradient.
  
          Args:
              grad_arr:       `np.ndarray` of gradients.
              fix_opt_flag:   If `False`, no optimization in this model will be done.
          
          Returns:
              `np.ndarray` of delta or gradients.
          '''
          if grad_arr.ndim > 3:
              grad_arr = grad_arr.reshape((
                  grad_arr.shape[0],
                  grad_arr.shape[1],
                  -1
              ))
  
          delta_arr, grads_list = self.__lstm_model.back_propagation(self.__pred_arr, grad_arr)
  
          if fix_opt_flag is False:
              self.__lstm_model.optimize(
                  grads_list,
                  self.__learning_rate,
                  1
              )
  
          return delta_arf learn(self, grad_arr, fix_opt_flag=False):
          '''
          Update this Discriminator by ascending its stochastic gradient.
  
          Args:
              grad_arr:       `np.ndarray` of gradients.
              fix_opt_flag:   If `False`, no optimization in this model will be done.
          
          Returns:
              `np.ndarray` of delta or gradients.
          '''
          if grad_arr.ndim > 3:
              grad_arr = grad_arr.reshape((
                  grad_arr.shape[0],
                  grad_arr.shape[1],
                  -1
              ))
  
          delta_arr, grads_list = self.__lstm_model.back_propagation(self.__pred_arr, grad_arr)
  
          if fix_opt_flag is False:
              self.__lstm_model.optimize(
                  grads_list,
                  self.__learning_rate,
                  1
              )
  
          return delta_arr
docs: Update this Discriminator by ascending its stochastic gradient.
  
          Args:
              grad_arr:       `np.ndarray` of gradients.
              fix_opt_flag:   If `False`, no optimization in this model will be done.
          
          Returns:
              `np.ndarray` of delta or gradients.