code: @Override
    public boolean containsAll(IntSet c)
    {
      if (c == null || c.isEmpty() || c == this) {
        return true;
      }
      if (isEmpty()) {
        return false;
      }
  
      final FastSet other = convert(c);
  
      if (other.firstEmptyWord > firstEmptyWord) {
        return false;
      }
  
      final int[] localWords = words;       // faster
      final int[] localOtherWords = other.words;   // faster
      for (int i = 0; i < other.firstEmptyWord; i++) {
        int o = localOtherWords[i];
        if ((localWords[i] & o) != o) {
          return false;
        }
      }
      return true;
    }
docs: {@inheritDoc}