code: def __init__(self, bert_encoder, config):
      super(BertPretrainingLoss, self).__init__(config)
      self.bert = bert_encoder
      self.cls = BertPreTrainingHeads(
          config, self.bert.embeddings.word_embeddings.weight
      )
      self.cls.apply(self.init_bert_weights)
  
imports: import torch
  import torch.nn
  from torch.nn import CrossEntropyLoss, MSELoss
  from turing.utils import TorchTuple
  from pytorch_pretrained_bert.modeling import BertModel
  from pytorch_pretrained_bert.modeling import BertPreTrainingHeads, PreTrainedBertModel, BertPreTrainingHeads
  from pytorch_pretrained_bert.file_utils import PYTORCH_PRETRAINED_BERT_CACHE
label_desc: Use image node_id 1 to create a new BertPretrainingLoss object from inherited base classes: PreTrainedBertModel with example: obj = BertPretrainingLoss(bert_encoder, config)