How to use the voila.static_file_handler.MultiStaticFileHandler function in voila

static_path='/',
            server_root_dir='/',
            contents_manager=self.contents_manager,
            config_manager=self.config_manager
        )

        self.app.settings.update(self.tornado_settings)

        handlers = []

        handlers.extend([
            (url_path_join(self.server_url, r'/api/kernels/%s' % _kernel_id_regex), KernelHandler),
            (url_path_join(self.server_url, r'/api/kernels/%s/channels' % _kernel_id_regex), ZMQChannelsHandler),
            (
                url_path_join(self.server_url, r'/voila/static/(.*)'),
                MultiStaticFileHandler,
                {
                    'paths': self.static_paths,
                    'default_filename': 'index.html'
                }
            )
        ])

        # Serving notebook extensions
        if self.voila_configuration.enable_nbextensions:
            handlers.append(
                (
                    url_path_join(self.server_url, r'/voila/nbextensions/(.*)'),
                    FileFindHandler,
                    {
                        'path': self.nbextensions_path,
                        'no_cache_paths': ['/'],  # don't cache anything in nbextensions

host_pattern = '.*$'
    base_url = url_path_join(web_app.settings['base_url'])

    tree_handler_conf = {
        'voila_configuration': voila_configuration
    }
    web_app.add_handlers(host_pattern, [
        (url_path_join(base_url, '/voila/render/(.*)'), VoilaHandler, {
            'config': server_app.config,
            'nbconvert_template_paths': nbconvert_template_paths,
            'voila_configuration': voila_configuration
        }),
        (url_path_join(base_url, '/voila'), VoilaTreeHandler, tree_handler_conf),
        (url_path_join(base_url, '/voila/tree' + path_regex), VoilaTreeHandler, tree_handler_conf),
        (url_path_join(base_url, '/voila/static/(.*)'), MultiStaticFileHandler, {'paths': static_paths}),
        (
            url_path_join(base_url, r'/voila/files/(.*)'),
            WhiteListFileHandler,
            {
                'whitelist': voila_configuration.file_whitelist,
                'blacklist': voila_configuration.file_blacklist,
                'path': os.path.expanduser(web_app.settings['server_root_dir']),
            },
        ),
    ])

    # Serving notebook extensions
    if voila_configuration.enable_nbextensions:
        # First look into 'nbextensions_path' configuration key (classic notebook)
        # and fall back to default path for nbextensions (jupyter server).
        if 'nbextensions_path' in web_app.settings:

def initialize(self, paths, default_filename=None):
        self.roots = paths
        super(MultiStaticFileHandler, self).initialize(path=paths[0], default_filename=default_filename)