text: const { NotImplementedError } = require('../extensions/index.js');
  
  /**
   * Implement the Stack with a given interface via array.
   *
   * @example
   * const stack = new Stack();
   *
   * stack.push(1); // adds the element to the stack
   * stack.peek(); // returns the peek, but doesn't delete it, returns 1
   * stack.pop(); // returns the top element from stack and deletes it, returns 1
   * stack.pop(); // undefined
   *
   */
  class Stack {
  	constructor () {
  		this._stack = []
  	}
  
    push(element) {
      this._stack.push(element)
    }
  
    pop() {
  		if (this._stack.length) {
  			return this._stack.pop()
  		}
    }
  
    peek() {
  		const id = this._stack.length - 1
      return this._stack[id]
    }
  }
  
  module.exports = {
    Stack
  };
  