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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def main():
 """Entry point from command line"""

    parser = get_parser()
    args = parser.parse_args()

    if args.debug:
        logger.setLevel(logging.NOTSET)

    initialize_preferences()

    if args.version:
        print(__version__)
        return

    cmd = args.cmd or args.args

    if args.no_browser and args.browser:
        print("Cannot specify no-browser and browser. Must specify one or the other.")
        exit(1)

    app.config["initial_binary_and_args"] = cmd
    app.config["gdb_args"] = shlex.split(args.gdb_args)
    app.config["rr"] = args.rr
    app.config["gdb_path"] = args.gdb
    app.config["show_gdbgui_upgrades"] = not args.hide_gdbgui_upgrades
    app.config["gdbgui_auth_user_credentials"] = get_gdbgui_auth_user_credentials(
        args.auth_file, args.user, args.password
    )
    app.config["project_home"] = args.project
    if args.remap_sources:
        try:
            app.config["remap_sources"] = json.loads(args.remap_sources)
        except json.decoder.JSONDecodeError as e:
            print(
                "The '--remap-sources' argument must be valid JSON. See gdbgui --help."
            )
            print(e)
            exit(1)

    if args.license:
        print("saving license information")
        save_license(args.license)

    verify_gdb_exists(app.config["gdb_path"])
    if args.remote:
        args.host = "0.0.0.0"
        args.no_browser = True
        if app.config["gdbgui_auth_user_credentials"] is None:
            print(
                "Warning: authentication is recommended when serving on a publicly "
                "accessible IP address. See gdbgui --help."
            )

    if warn_startup_with_shell_off(platform.platform().lower(), args.gdb_args):
        logger.warning(
            "You may need to set startup-with-shell off when running on a mac. i.e.\n"
            "  gdbgui --gdb-args='--init-eval-command=\"set startup-with-shell off\"'\n"
            "see http://stackoverflow.com/questions/39702871/gdb-kind-of-doesnt-work-on-macos-sierra\n"
            "and https://sourceware.org/gdb/onlinedocs/gdb/Starting.html"
        )

    setup_backend(
        serve=True,
        host=args.host,
        port=int(args.port),
        debug=bool(args.debug),
        open_browser=(not args.no_browser),
        browsername=args.browser,
        private_key=args.key,
        certificate=args.cert,
    )