How to use the wpgtk.data.themer.set_theme function in wpgtk

if args.backend in pywal.colors.list_backends():
            settings['backend'] = args.backend
        else:
            logging.error("no such backend, please "
                          "choose a valid backend")
            exit(1)

    if args.preview:
        pywal.colors.palette()
        exit(0)

    if args.m:
        file_list = files.get_file_list()
        if len(file_list) > 0:
            filename = random.choice(file_list)
            themer.set_theme(filename, filename, args.r)
            exit(0)
        else:
            logging.error("you have no themes")
            exit(1)

    if args.s:
        if len(args.s) == 1:
            themer.set_theme(args.s[0], args.s[0], args.r)
        elif len(args.s) == 2:
            themer.set_theme(args.s[0], args.s[1], args.r)
        exit(0)

    if args.l:
        if args.t:
            templates = files.get_file_list(OPT_DIR, False)
            any(print(t) for t in templates if ".base" in t)

if args.m:
        file_list = files.get_file_list()
        if len(file_list) > 0:
            filename = random.choice(file_list)
            themer.set_theme(filename, filename, args.r)
            exit(0)
        else:
            logging.error("you have no themes")
            exit(1)

    if args.s:
        if len(args.s) == 1:
            themer.set_theme(args.s[0], args.s[0], args.r)
        elif len(args.s) == 2:
            themer.set_theme(args.s[0], args.s[1], args.r)
        exit(0)

    if args.l:
        if args.t:
            templates = files.get_file_list(OPT_DIR, False)
            any(print(t) for t in templates if ".base" in t)
        else:
            print("\n".join(files.get_file_list()))
        exit(0)

    if args.version:
        print("current version: " + __version__)
        exit(0)

    if args.d:
        delete_action = files.delete_template if args.t \

pywal.colors.palette()
        exit(0)

    if args.m:
        file_list = files.get_file_list()
        if len(file_list) > 0:
            filename = random.choice(file_list)
            themer.set_theme(filename, filename, args.r)
            exit(0)
        else:
            logging.error("you have no themes")
            exit(1)

    if args.s:
        if len(args.s) == 1:
            themer.set_theme(args.s[0], args.s[0], args.r)
        elif len(args.s) == 2:
            themer.set_theme(args.s[0], args.s[1], args.r)
        exit(0)

    if args.l:
        if args.t:
            templates = files.get_file_list(OPT_DIR, False)
            any(print(t) for t in templates if ".base" in t)
        else:
            print("\n".join(files.get_file_list()))
        exit(0)

    if args.version:
        print("current version: " + __version__)
        exit(0)

def on_set_clicked(self, widget):
        x = self.option_combo.get_active()
        y = self.colorscheme.get_active()
        current_walls = files.get_file_list()
        if current_walls:
            filename = current_walls[x]
            colorscheme_file = current_walls[y]
            themer.set_theme(filename, colorscheme_file)