static <A> L<A> lineComp_listWithGap(l, int copyTo, int copyFrom) {
  if (copyFrom == copyTo) ret l;
  ret new RandomAccessAbstractList<A> {
    public int size() { ret l-(copyTo-copyFrom); }
    public A get(int i) {
      ret l.get(i < copyTo ? i : i+(copyTo-copyFrom));
    }
  };
}