export class Stack {
    constructor(...items) {
        this._items = []

        items.forEach(item => this._items.push(item));
    }

    push(...items) {
        items.forEach(item => this._items.push(item));
    }

    pop() {
        if (this._items.length > 0)
            return this._items.pop();

        return null;
    }

    peek() {
        if (this._items.length > 0)
            return this._items[this._items.length - 1];

        return null;
    }

    size() {
        return this._items.length;
    }

    isEmpty() {
        return this.size() === 0;
    }
}