* Prototype
-Every object in JavaScript has a built-in property,
which is called its prototype.
-The prototype is itself an object, so the prototype will
have its own prototype, making what iss called a prototype chain.
-The chain ends when we reach a prototype that has null for
its own prototype.
-Prototypes are the mechanism by which JavaScript objects inherit
features from one another
const arr = [1,2,3,4]
// proto type : arr.__proto__
// prototype chain : arr.__proto__.__proto__.__proto__