code: def _get_error_message(
      cls,
      max_sentences,
      max_tokens,
      bsz_mult,
      num_tokens_vec,
      validation,
      results,
  ):
      return f"""Reference batch_by_size implementation should produce
                      same output as the baseline method.
                  Params:
                  max_sentences={max_sentences},
                  max_tokens={max_tokens},
                  bsz_mult={bsz_mult},
                  num_tokens_vec={num_tokens_vec},
                  expected_batches={validation},
                  returned_batches={results}"""
  
file_path: fairseq/tests/test_data_utils.py
imports: import unittest
  import numpy
  from fairseq.data.data_utils_fast import batch_by_size_fn, batch_by_size_vec
label_desc: Use image node_id 2 for calling the TestBatchBySize obj's underlying member method code with example usage: obj._get_error_message(cls, max_sentences, max_tokens, bsz_mult, num_tokens_vec, validation, results) and returns: str, max_sentences, str, max_tokens, str, bsz_mult, str, num_tokens_vec, str, validation, str, results