code: @Override
    public boolean contains(int element)
    {
      if (element < 0) {
        throw new IndexOutOfBoundsException("element < 0: " + element);
      }
      if (isEmpty()) {
        return false;
      }
      return findElementOrEmpty(element) >= 0;
    }
docs: Returns <tt>true</tt> if this set contains the specified element.
  
  @param element element whose presence in this set is to be tested.
  
  @return <tt>true</tt> if this set contains the specified element.