/*
 *
 * Basic function using anonymous function
 * 功能：建立一個使用了anonymous function回傳num1-num2的function
 * 
 */
 let calc = function(num1, num2, callback){
	 return callback(num1, num2);
 }
 
 console.log("2 - 3 = " + calc(2, 3, function(num1, num2){
	return num1 - num2
 }));