/** ******************************
 * Hong Kong mobile phone number *
 *********************************/
/**
 * 4, 7, 8 heading are allowed since 2018
 * news: https://skypost.ulifestyle.com.hk/article/2006268/
 * */
export declare function is_hk_mobile_phone_prefix(tel: string): boolean;
/**
 * with/without +852 prefix
 * */
export declare function is_hk_mobile_phone(tel: number | string): boolean;
/**
 * very forgiving
 *
 * @return +852xxxxyyyy if valid
 *         empty string if not valid
 * */
export declare function to_full_hk_mobile_phone(tel: string | number): string;
/**
 * @returns +852 xxxx yyyy if valid
 */
export declare function format_hk_mobile_phone(tel: string | number): string;