def _diff_and_summarize(from_csv, to_csv, index_columns, stream=sys.stdout,
                        sep=',', ignored_columns=None, significance=None):
    """
    Print a summary of the difference between the two files.
    """
    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)
Print a summary of the difference between the two files.