b: for (var _iterator = d(), _isArray = Array.isArray(_iterator), _i = 0, _iterator = _isArray ? _iterator : _iterator[Symbol.iterator]();;) {
  var _ref;

  if (_isArray) {
    if (_i >= _iterator.length) break;
    _ref = _iterator[_i++];
  } else {
    _i = _iterator.next();
    if (_i.done) break;
    _ref = _i.value;
  }

  let c = _ref;

  for (var _iterator2 = f(), _isArray2 = Array.isArray(_iterator2), _i2 = 0, _iterator2 = _isArray2 ? _iterator2 : _iterator2[Symbol.iterator]();;) {
    var _ref2;

    if (_isArray2) {
      if (_i2 >= _iterator2.length) break;
      _ref2 = _iterator2[_i2++];
    } else {
      _i2 = _iterator2.next();
      if (_i2.done) break;
      _ref2 = _i2.value;
    }

    let e = _ref2;
    continue b;
  }
}
