let stack = []
stack.push(2) // stack is now [ 2 ]
stack.push(5) // stack is now [ 2, 5 ]
let lastElement = stack[stack.length - 1] // the las element is 5
let i = stack.pop() // stack is now [ 2 ]
console.log(i) // displays 5
let queue = []
queue.push(2) // queue is now [ 2 ]
queue.push(5) // queue is now [ 2, 5 ]
let i = queue.shift() // queue is now [ 5 ]
console.log(i) // displays 2