Question from the Node.js test

What will be the output of the console.log?
The following code implements the ES2015 specification

var reallyWeirdGenerator = function* (index) {
  yield index++;
  yield index + 5;
  yield index;
};

var iterator = reallyWeirdGenerator(0);
iterator.next();
iterator.next();
iterator.next();
console.log(iterator.next().done);