/**
 * Return Downcast's documented `downcast://` URL scheme.
 *
 * @returns Downcast URL scheme.
 * @example
 * open()
 * // => 'downcast://'
 * @link https://support.downcast.fm/article/efmhyEOyOj-url-schemes-opening-feed-ur-ls-mac
 */
export declare function open(): string;