def train_step_and_backward_closure():
    result = self.training_step_and_backward(split_batch, batch_idx, opt_idx, optimizer, self.trainer.hiddens)
    return (None if (result is None) else result.loss)
def train_step_and_backward_closure():
    result = self.training_step_and_backward(split_batch, batch_idx, opt_idx, optimizer, self.trainer.hiddens)
    return (None if (result is None) else result.loss)