export declare class Levels<T> {
    private level_;
    push(level: T[]): void;
    pop(): T[];
    peek(): T[];
    indexOf(element: T): number | null;
    find(pred: (p1: T) => boolean): T | null;
    get(index: number): T | null;
    depth(): number;
    clone(): Levels<T>;
    toString(): string;
}
