https://nomadcoders.co/javascript-for-beginners/lectures/2867
const calculator = {
plus : function(a,b){
console.log(a+b);
},
minus : function(a,b){
console.log(a-b);
},
mul : function(a,b){
console.log(a*b);
},
divide : function(a,b){
console.log(a/b);
},
pow : function(a,b){
console.log(a**b);
},
};