export declare class MayBe<T> {
    value: T;
    constructor(value: T);
    static of<U>(value: U): MayBe<U>;
    isNothing(): boolean;
    map<R>(callback: (arg: null | undefined) => R): MayBe<null | undefined>;
    map<R>(callback: (arg: T) => R): MayBe<R>;
    join(): T | MayBe<any>;
    chain<R>(callback: (arg: T) => R): MayBe<any>;
}