def pytest_benchmark_group_stats(config, benchmarks, group_by):
    """
    You may perform grouping customization here, in case the builtin grouping doesn't suit you.

    Example:

    .. sourcecode:: python

        @pytest.mark.hookwrapper
        def pytest_benchmark_group_stats(config, benchmarks, group_by):
            outcome = yield
            if group_by == "special":  # when you use --benchmark-group-by=special
                result = defaultdict(list)
                for bench in benchmarks:
                    # `bench.special` doesn't exist, replace with whatever you need
                    result[bench.special].append(bench)
                outcome.force_result(result.items())
    """
    pass
