/**
 * Gets the user's LINE version.
 * @export
 * @returns {string|null} LINE Version, if inside LINE client. Null, otherwise
 * @example
 * const lineVersion = liff.getLineVersion()
 * if (!lineVersion || lineVersion === '9.1.0') {
 *   // do something
 * }
 */
export default function getLineVersion(): string | null;