function counter() {
    let count = 0

    return {
       increment() {
           console.log(++count)
       },
       decrement() {
           console.log(--count)
       }
    }   
}

console.log("Hello world!");

let c = counter()
c.increment()
c.increment()
c.decrement()
c.decrement()
console.log(c.count)