export declare class ListItem<T> {
    value: T;
    next?: ListItem<T>;
    previous?: ListItem<T>;
    constructor(value: T);
    insertNext(next: ListItem<T>): ListItem<T>;
    insertNext(value: T): ListItem<T>;
    insertPrevious(previous: ListItem<T>): ListItem<T>;
    insertPrevious(value: T): ListItem<T>;
    private static toItem;
}
export declare class NullListItem extends ListItem<any> {
    constructor();
}