@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (this.getClass() != obj.getClass() || obj == null)
			return false;
		
		Edge e = (Edge)obj;
		
		return (n1 == e.n1) && (n2 == e.n2) ||
				(n2 == e.n1) && (n1 == e.n2); // TODO should i support multigraphs? beacuse currently i exclude them with this code 
	}