code: def get_decoder_lang_id(self, lang_code):
      return self.decoder_langs.index(lang_code)
  
imports: import os
  from collections import OrderedDict
  from typing import Dict, List, Optional, Tuple
  import numpy
  from fairseq import data, options
  from fairseq.data import ConcatDataset, LanguagePairDataset, NoisingDataset
  from fairseq.data.multi_corpus_sampled_dataset import MultiCorpusSampledDataset
  from fairseq.data.noising import UnsupervisedMTNoising
  from fairseq.tasks import LegacyFairseqTask, register_task
  from pytorch_translate import constants, utils
  from pytorch_translate.data import char_data, data, dictionary, utils, weighted_data
  from pytorch_translate.data.language_pair_upsampling_dataset import LanguagePairUpsamplingDataset
  from pytorch_translate.research.multisource import multisource_data
label_desc: Use image node_id 7 for calling the PytorchTranslateMultilingualTask obj's underlying member method code with example usage: obj.get_decoder_lang_id(lang_code) and returns: self