Yielding generator from a generator: seemless to the client code

yield_generator_from_generator.js

function* func1() {
  var y = yield 'b';
  console.log('y = ', y);
  return 'c';
}

function* func() {
  var x = yield 'a'
  console.log("x = ", x);
  var z = yield* func1();
  console.log("z = ", z);
  return 'd';
}

var i = 0;
var it = func();
var next = it.next();

while (!next.done) {
  console.log(next);
  next = it.next(i++);
}

//Object { value="a",  done=false}
//x = 0
//Object { value="b",  done=false}
//y = 1
//z = c
//Object { value="d",  done=true}