code: def __init__(self, args, common_dict, mono_langs, valid_lang_pairs):
      super().__init__(args, common_dict, common_dict)
      self.common_dict = common_dict
      self.mono_langs = mono_langs
      self.valid_lang_pairs = valid_lang_pairs
  
      self.SHOW_SAMPLES_INTERVAL = 1000
      # Start by showing samples
      self._show_samples_ctr = self.SHOW_SAMPLES_INTERVAL
      self.SHOW_SAMPLES_NUMBER = 5
      self.lambda_bt = PiecewiseLinearFn.from_string(args.lambda_bt)
      self.lambda_dae = PiecewiseLinearFn.from_string(args.lambda_dae)
  
      self.args = args
      self.data = utils.split_paths(self.args.data)
      if len(self.data) == 1:
          shards = list(Path(self.data[0]).glob("shard*"))
          if len(shards) > 0:
              # keep this as strings, since it can also be a manifold path
              old_data = self.data
              self.data = [str(shard) for shard in shards]
              logging.warning(
                  f"Expanded data directory {old_data} to {self.data}"
              )
  
imports: import contextlib
  import json
  import logging
  import math
  import os
  from argparse import Namespace
  from collections import OrderedDict, defaultdict
  from pathlib import Path
  from typing import Dict, Sequence, Tuple
  from argparse import ArgumentError
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
  import fairseq
  from fairseq import options, utils
  from fairseq.logging import metrics
  from fairseq.data import FairseqDataset, LanguagePairDataset, NoisingDataset, PrependTokenDataset, RoundRobinZipDatasets, TransformEosLangPairDataset, data_utils, encoders
  from fairseq.sequence_generator import SequenceGenerator
  from fairseq.tasks import register_task
  from fairseq.tasks.translation import TranslationTask, load_langpair_dataset
label_desc: Use image node_id 2 to create a new OnlineBackTranslationTask object from inherited base classes: TranslationTask with example: obj = OnlineBackTranslationTask(args, common_dict, mono_langs, valid_lang_pairs)