code: def _diff_and_summarize(from_csv, to_csv, index_columns, stream=sys.stdout,
                          sep=',', ignored_columns=None, significance=None):
      
      from_records = list(records.load(from_csv, sep=sep))
      to_records = records.load(to_csv, sep=sep)
  
      diff = patch.create(from_records, to_records, index_columns, ignored_columns)
      if significance is not None:
          diff = patch.filter_significance(diff, significance)
  
      _summarize_diff(diff, len(from_records), stream=stream)
      exit_code = (EXIT_SAME
                   if patch.is_empty(diff)
                   else EXIT_DIFFERENT)
      sys.exit(exit_code)
docs: Print a summary of the difference between the two files.