/**
 * A stack collection (supports LIFO operations).
 *
 * @public
 */
export default class Stack {
    /**
     * Adds an item to the stack.
     *
     * @public
     * @param {object} item
     * @returns {object} - The item added to the stack.
     */
    public push(item: object): object;
    /**
     * Removes and returns an item from the stack. Throws if the stack is empty.
     *
     * @public
     * @returns {object} - The removed from the stack.
     */
    public pop(): object;
    /**
     * Returns the next item in the stack (without removing it). Throws if the stack is empty.
     *
     * @public
     * @returns {object} - The item added to the stack.
     */
    public peek(): object;
    /**
     * Returns true if the stack is empty; otherwise false.
     *
     * @public
     * @returns {boolean}
     */
    public empty(): boolean;
    /**
     * Runs an action on each item in the stack.
     *
     * @public
     * @param {Function} action - The action to run.
     */
    public scan(action: Function): void;
    /**
     * Outputs an array of the stack's items; without affecting the
     * stack's internal state;
     *
     * @public
     * @returns {Array}
     */
    public toArray(): any[];
    /**
     * Returns a string representation.
     *
     * @public
     * @returns {string}
     */
    public toString(): string;
    #private;
}