function sayHello() {
    console.log("Hello World");
}
sayHello(); // Hello World

function addFunction(a, b) {
    console.log(a+b);
}
addFunction(3,5); // 8

const sum = (function() {
  "use strict";
  return function sum(...args) {
    let sumNum = 0;
    for (let i = 0; i<args.length;i++){
      sumNum += args[i];
    }
    return sumNum; 
  };
})();
console.log(sum(1, 2, 3)); // 6

function queue(arr,item) {
    arr.push(item);
    return arr.shift(); // return the shifted value in the array.
}

var testArr = [3,4,5,6,7];

console.log("Before: " + JSON.stringify(testArr)); // [3,4,5,6,7]
console.log(queue(testArr, 8)); // 3
console.log("After: " + JSON.stringify(testArr)); // [4,5,6,7,8]