simple last-in-first-out(LIFO) data structure
var Stack = require('stack-ll')
var s = new Stack()
s.push('hello')
s.push('world')
console.log(s.pop())
console.log(s.pop())
Creates a new stack object
pushes val into stack object
removes top of stack element and return its value
returns length of the stack
Iterate over each value of stack using callback
MIT