def create_main_parser():
    # type: () -> ConfigOptionParser
    """Creates and returns the main parser for pip's CLI
    """

    parser_kw = {
        'usage': '\n%prog <command> [options]',
        'add_help_option': False,
        'formatter': UpdatingDefaultsHelpFormatter(),
        'name': 'global',
        'prog': get_prog(),
    }

    parser = ConfigOptionParser(**parser_kw)
    parser.disable_interspersed_args()

    pip_pkg_dir = os.path.abspath(os.path.join(
        os.path.dirname(__file__), "..", "..",
    ))
    parser.version = 'pip %s from %s (python %s)' % (
        __version__, pip_pkg_dir, sys.version[:3],
    )

    # add the general options
    gen_opts = cmdoptions.make_option_group(cmdoptions.general_group, parser)
    parser.add_option_group(gen_opts)

    # so the help formatter knows
    parser.main = True  # type: ignore

    # create command listing for description
    command_summaries = get_summaries()
    description = [''] + ['%-27s %s' % (i, j) for i, j in command_summaries]
    parser.description = '\n'.join(description)

    return parser
Creates and returns the main parser for pip's CLI
    
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_internal/cli/main_parser.py