code: def forward(
      self,
      prediction_scores,
      masked_lm_labels,
      next_sentence_labels=None,
  ):
      masked_lm_loss = self.loss_fn(
          prediction_scores.view(-1, self.vocab_size),
          masked_lm_labels.view(-1),
      )
      # next_sentence_loss = self.loss_fn(seq_relationship_score.view(-1, 2), next_sentence_labels.view(-1))
      total_loss = masked_lm_loss  # + next_sentence_loss
      return total_loss
  
imports: import torch
label_desc: Use image node_id 2 for calling the LossForPretraining obj's underlying member method code with example usage: obj.forward(prediction_scores, masked_lm_labels, next_sentence_labels) and returns: total_loss