static Set<S> aggressivelyCollectPossibleMD5s(S s) {
  new HashSet<S> ids;
  aggressivelyCollectPossibleMD5s(s, ids);
  ret ids;
}

static void aggressivelyCollectPossibleMD5s(S s, Set<S> out) {
  if (s == null) ret;
  for i over s: {
    int j = i;
    while (j < l(s) && isLowerHexChar(s.charAt(j))) ++j;
    if (j-i == 32)
      addIfPossibleMD5(out, substring(s, i, j));
    i = j;
  }
}