code: private int get_size_i(final boolean fwd) {
  	int size = 0;
  	final Iterator it = elements.iterator();
  	while (it.hasNext()) {
  	    final GroupElement e = (GroupElement) it.next();
  	    if (e instanceof GroupDeviceElement || fwd) {
  		size += e.get_size(true);
  	    }
  	}
  	return size;
      }
docs: Returns the group's size - internal impl