text: function* task1() {
      console.log(1);
      yield 1;
      console.log(1);
  }
  function* task2() {
      console.log(2);
      yield 2;
      console.log(2);
  }
  function* gen() {
      yield task1();
      yield task2();
  }
  let it = gen();
  let result = it.next();
  console.log(result);