static <A> ArrayList<Byte> byteArrayToList(byte[] a) {
  if (a == null) null;
  ret byteArrayToList(a, 0, a.length);
}

// no range checking on from/to in the interest of speed
static <A> ArrayList<Byte> byteArrayToList(byte[] a, int from, int to) {
  if (a == null) null;
  ArrayList<Byte> l = new(to-from);
  for (int i = from; i < to; i++) l.add(a[i]);
  ret l;
}