RL-Adventure/3.dueling dqn.ipynb missing forward?

[laz8]

def compute_td_loss(batch_size):
    state, action, reward, next_state, done = replay_buffer.sample(batch_size)

    state      = Variable(torch.FloatTensor(np.float32(state)))
    next_state = Variable(torch.FloatTensor(np.float32(next_state)))
    action     = Variable(torch.LongTensor(action))
    reward     = Variable(torch.FloatTensor(reward))
    done       = Variable(torch.FloatTensor(done))

    q_values      = current_model(state)
    next_q_values = target_model(next_state)

    q_value          = q_values.gather(1, action.unsqueeze(1)).squeeze(1)
    next_q_value     = next_q_values.max(1)[0]
    expected_q_value = reward + gamma * next_q_value * (1 - done)
    
    loss = (q_value - expected_q_value.detach()).pow(2).mean()
        
    optimizer.zero_grad()
    loss.backward()
    optimizer.step()
    
    return loss

no forward call?

edit: sry, found my issue caused by Variable not "the missing forward", it works without calling forward(), the result is the same, can be closed.