text: {
    var fn1 = 1;
    var fn2 = 1;
  
    while (1) {
      var current = fn2;
      fn2 = fn1;
      fn1 = fn1 + current;
      var reset = yield current;
  
      if (reset) {
        fn1 = 1;
        fn2 = 1;
      }
    }
  }