/**
 * Outputs a given string at specified position on screen.
 *
 * @param {any} string - String or value to be output.
 * @param {number} [x=-1] - X coordinate for output. Default is no specific position.
 * @param {number} [y=-1] - Y coordinate for output. Default is no specific position.
 * @returns {void}
 */
export declare function addch(string: any, x?: number, y?: number): void;