static String[] dropLast(String[] a, int n) {
  n = Math.min(n, a.length);
  String[] b = new String[a.length-n];
  System.arraycopy(a, 0, b, 0, b.length);
  return b;
}

static <A> L<A> dropLast(L<A> l) {
  ret subList(l, 0, l(l)-1);
}

static <A> L<A> dropLast(Iterable<A> l) {
  ret dropLast(asList(l));
}

static S dropLast(S s) {
  ret substring(s, 0, l(s)-1);
}