Object.prototype.forEach = function (f){
 var keys = Object.keys(this)
 keys.forEach(key => f(this[key],key,this))
 return this
}

/*

let fruits = {apple: 3, orange: 4, banana: 8}

// Print each fruit
fruits.forEach((count, fruit) => console.log("I have " + count + " " + fruit + "s")

// Increment each fruit by one
fruits.forEach((count, fruit, o) => o[fruit] += 1)

*/