Write a function named map that takes two arguments.
arr (array)
callback (function)
Return a new array where each element of arr is transformed by the callback function and the result is pushed into the new array.
For example:
var rounded = map([0.01, 2, 9.89, Math.PI], function(num) {
return Math.round(num);
});
console.log(rounded); // [0, 2, 10, 3]