export declare class Node<Item> {
    item: Item;
    next: Node<Item>;
}
/**
 *  The `Stack` class represents a last-in-first-out (LIFO) stack of generic items.
 *  It supports the usual <em>push</em> and <em>pop</em> operations, along with methods
 *  for peeking at the top item, testing if the stack is empty, and iterating through
 *  the items in LIFO order.
 *  <p>
 *  This implementation uses a singly linked list with a static nested class for
 *  linked-list nodes. See {@link LinkedStack} for the version from the
 *  textbook that uses a non-static nested class.
 *  See {@link ResizingArrayStack} for a version that uses a resizing array.
 *  The <em>push</em>, <em>pop</em>, <em>peek</em>, <em>size</em>, and <em>is-empty</em>
 *  operations all take constant time in the worst case.
 *  <p>
 *  For additional documentation,
 *  see <a href="https://algs4.cs.princeton.edu/13stacks">Section 1.3</a> of
 *  <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
 *
 *  @param <Item> the generic type of an item in this stack
 */
export default class Stack<Item> implements Iterable<Item> {
    private first;
    private n;
    private modCount;
    constructor();
    /**
     * Returns true if this stack is empty.
     *
     * @return  true if this stack is empty; false otherwise
     */
    isEmpty(): boolean;
    /**
     * Returns the number of items in this stack.
     *
     * @return  the number of items in this stack
     */
    size(): number;
    /**
     * Adds the item to this stack.
     *
     * @param   item the item to add
     */
    push(item: Item): void;
    /**
     * Removes and returns the item most recently added to this stack.
     *
     * @return  the item most recently added
     * @throws Error if this stack is empty
     */
    pop(): Item;
    /**
     * Returns (but does not remove) the item most recently added to this stack.
     *
     * @return  the item most recently added to this stack
     * @throws Error if this stack is empty
     */
    peek(): Item;
    /**
     * Returns a string representation of this stack.
     *
     * @return  the sequence of items in this stack in LIFO order, separated by spaces
     */
    toString(): string;
    /**
     * Returns an iterator to this stack that iterates through the items in LIFO order.
     *
     * @return  an iterator to this stack that iterates through the items in LIFO order
     */
    [Symbol.iterator](): {
        next(): IteratorResult<Item, any>;
    };
}