def pytest_addoption(parser):
    """
    register argparse-style options and ini-style config values.
    """
    output_options_group = parser.getgroup('Output Options')
    output_options_group.addoption('--sys-stats', default=False, action=
        'store_true', help=
        'Print System CPU and MEM statistics after each test execution.')
    output_options_group.addoption('--sys-stats-no-children', default=False,
        action='store_true', help=
        "Don't include child processes memory statistics.")
    output_options_group.addoption('--sys-stats-uss-mem', default=False,
        action='store_true', help=
        'Use the USS("Unique Set Size", memory unique to a process which would be freed if the process was terminated) memory instead which is more expensive to calculate.'
        )
