static O[] litparams(O... l) {
  int n = 0, n1 = l(l);
  for (int i = 0; i < n1; i += 2)
    if (l[i] != null && l[i+1] != null)
      ++n;
  if (n == 0) null;
  O[] params = new O[n*2];
  int j = 0;
  for (int i = 0; i < n1; i += 2) {
    O key = l[i], value = l[i+1];
    if (key != null && value != null) {
      params[j++] = key;
      params[j++] = value;
    }
  }
  ret params;
}