Implement the getInParallel function that should be used to invoke multiple API calls in parallel. The function accepts an array of functions that return a Promise. The function should return a Promise which should resolve to an array of results from the apiCalls argument.

For example, calling the following code should print "[ 'First API call!', 'Second API call!' ]":

let promise = getInParallel([() => Promise.resolve("First API call!"),
                             () => Promise.resolve("Second API call!")]);
if(promise) {
  promise.then((result) => console.log(result)).catch((err) => console.log(err));
}