// https://javascript.info/closure
// Garbage collection
function f() {
  let value = Math.random();

  return function() { console.log(value); };
}

// 3 functions in array, every one of them links to Lexical Environment
// from the corresponding f() run
//         LE   LE   LE
let arr = [f(), f(), f()];
arr[0]()
arr[1]()
arr[2]()