Iterable groups

Make the Group class from the previous exercise iterable.
If you used an array to represent the group’s members, don’t just return the iterator created by calling the Symbol.iterator method on the array.

// Your code here (and the code from the previous exercise)

for (let value of Group.from(["a", "b", "c"])) {
// → a
// → b
// → c

Borrowing a method

Earlier in the chapter I mentioned that an object’s hasOwnProperty can be used as a more robust alternative to the in operator when you want to ignore the prototype’s properties. But what if your map needs to include the word "hasOwnProperty"?
Can you think of a way to call hasOwnProperty on an object that has its own property by that name?

let map = {one: true, two: true, hasOwnProperty: true};

// Fix this call
// → true