export declare function peekable<T>(it: Iterator<T, void, undefined>): PeekableIterator<T>;
export declare class PeekableIterator<out T = unknown> implements Iterable<T>, Iterator<T, void, undefined> {
    #private;
    private readonly it;
    constructor(it: Iterator<T, void, undefined>);
    [Symbol.iterator](): this;
    next(): IteratorResult<T, void>;
    peekNth(n: number): IteratorResult<T, void>;
}