The main entrypoint.

def main():
    """The main entrypoint."""
    from optparse import OptionParser

    parser = OptionParser(usage="%prog [options]")
    parser.add_option(
        "--werkzeug-path",
        "-p",
        dest="path",
        default="..",
        help="the path to the werkzeug package. defaults to cwd",
    )
    parser.add_option(
        "--compare",
        "-c",
        dest="compare",
        nargs=2,
        default=False,
        help="compare two hg nodes of Werkzeug",
    )
    parser.add_option(
        "--init-compare",
        dest="init_compare",
        action="store_true",
        default=False,
        help="Initializes the comparison feature",
    )
    options, args = parser.parse_args()
    if args:
        parser.error("Script takes no arguments")
    if options.compare:
        compare(*options.compare)
    elif options.init_compare:
        init_compare()
    else:
        run(options.path)