@Contract(pure=true)
  public static <T> int indexOfIdentity(@NotNull List<? extends T> list, T element) {
    for (int i = 0, listSize = list.size(); i < listSize; i++) {
      if (list.get(i) == element) {
        return i;
      }
    }
    return -1;
  }
@Contract(pure=true)
  public static <T> int indexOfIdentity(@NotNull List<? extends T> list, T element)