code: public boolean add(E e) {
          typeCheck(e);
  
          int eOrdinal = e.ordinal();
          int eWordNum = eOrdinal >>> 6;
  
          long oldElements = elements[eWordNum];
          elements[eWordNum] |= (1L << eOrdinal);
          boolean result = (elements[eWordNum] != oldElements);
          if (result)
              size++;
          return result;
      }
docs: Adds the specified element to this set if it is not already present.
  
  @param e element to be added to this set
  @return <tt>true</tt> if the set changed as a result of the call
  
  @throws NullPointerException if <tt>e</tt> is null