if (i1.hasNext()) {
                            res1 = i1.next();
                        } else {
                            done = true;
                        }
                    }
                } else {
                    // move on to next in r1
                    if (i1.hasNext()) {
                        res1 = i1.next();
                    } else {

@user_router.get("/{user_id}")
def get_user(user_id: str):
    return {"user_id": user_id}


@item_router.get("/")
def get_items(user_id: Optional[str] = None):
    if user_id is None:
        return [{"item_id": "i1", "user_id": "u1"}, {"item_id": "i2", "user_id": "u2"}]
    else:
        return [{"item_id": "i2", "user_id": user_id}]


@item_router.get("/{item_id}")
def get_item(item_id: str, user_id: Optional[str] = None):

    // Test data
    List<String> list = new ArrayList<>(asList("a", "b"));

    // Test & Verify
    Iterator<String> i1 = Iterables.consumingIterable(list).iterator();
    Iterator<String> i2 = Iterables.consumingIterable(list).iterator();

    i1.next();
    assertThrows(ConcurrentModificationException.class, () -> i2.next());
  }

  public void testConsumingIterable_queue_iterator() {

	encOff = encCumulativeSum + startPkgNum*sseDAREEncPackageBlockSize
	// Locate the part containing the end of the required range
	endOffset := off + length - 1
	for i1, size := range sizes[partStart:] {
		i := partStart + i1
		if endOffset < cumulativeSum+size {
			partEnd = i
			break
		}
		cumulativeSum += size
		encPartSize, _ := sio.EncryptedSize(uint64(size))