/**
 * Start or switch focus to the Skype client.
 *
 * @returns Skype focus URL.
 * @example
 * open()
 * // => 'skype:'
 * @link https://learn.microsoft.com/en-us/skype-sdk/skypeuris/skypeuriapireference#startswitch-focus-to-the-skype-client
 */
export declare function open(): string;