import { type Option } from './option.js';
/**
 *  Return one of this pattern:
 *
 *  1. a=Some, b=None => _a_
 *  2. a=None, b=Some => _b_
 *  3. Others => `None`
 */
export declare function xorForOption<T>(a: Option<T>, b: Option<T>): Option<T>;