code: def build_decoder(cls, args, tgt_dict, embed_tokens):
      decoder = NATransformerDecoder(args, tgt_dict, embed_tokens)
      if getattr(args, "apply_bert_init", False):
          decoder.apply(init_bert_params)
      return decoder
  
imports: import torch
  import torch.nn.functional
  from fairseq import utils
  from fairseq.iterative_refinement_generator import DecoderOut
  from fairseq.models import register_model, register_model_architecture
  from fairseq.models.nat import FairseqNATDecoder, FairseqNATModel, ensemble_decoder
  from fairseq.models.transformer import Embedding
  from fairseq.modules.transformer_sentence_encoder import init_bert_params
label_desc: Use image node_id 3 for calling the NATransformerModel obj's underlying member method code with example usage: obj.build_decoder(cls, args, tgt_dict, embed_tokens) and returns: decoder