code: def _get_dataset(self, n_obs=1000, max_len=128):
      if os.getenv("USE_REAL_DATA", False):
          data_dir = "examples/seq2seq/wmt_en_ro"
          max_tokens = max_len * 2 * 64
          if not Path(data_dir).joinpath("train.len").exists():
              save_len_file(MARIAN_TINY, data_dir)
      else:
          data_dir = "examples/seq2seq/test_data/wmt_en_ro"
          max_tokens = max_len * 4
          save_len_file(MARIAN_TINY, data_dir)
  
      tokenizer = AutoTokenizer.from_pretrained(MARIAN_TINY)
      ds = Seq2SeqDataset(
          tokenizer,
          data_dir=data_dir,
          type_path="train",
          max_source_length=max_len,
          max_target_length=max_len,
          n_obs=n_obs,
      )
      return ds, max_tokens, tokenizer
  
imports: import os
  from pathlib import Path
  import numpy
  import pytest
  from torch.utils.data import DataLoader
  from pack_dataset import pack_data_dir
  from parameterized import parameterized
  from save_len_file import save_len_file
  from transformers import AutoTokenizer
  from transformers.models.mbart.modeling_mbart import shift_tokens_right
  from transformers.testing_utils import TestCasePlus, slow
  from utils import FAIRSEQ_AVAILABLE, DistributedSortishSampler, LegacySeq2SeqDataset, Seq2SeqDataset
label_desc: Use image node_id 6 for calling the TestAll obj's underlying member method code with example usage: obj._get_dataset(n_obs, max_len) and returns: ds,  max_tokens,  tokenizer