return _v.remove(ge);
_e.removeAll(((DVertex) ge).inEdges()); _e.removeAll(((DVertex) ge).outEdges()); _v.remove(ge); cleanupVertex(((DVertex) ge).neighbors());  return true;
	public boolean remove(GraphElement ge) {		if(ge.getClass() == DVertex.class) {			return _v.remove(ge);		}		if(ge.getClass() == DEdge.class) {			return _e.remove(ge);		}		/* TODO: need to add cases for other types here */		throw new IllegalArgumentException("You must add a Directed graph element to a Directed Graph.");	}