public static DenseEdgeList fromSparse(SparseEdgeList list) {
	byte[] keys = list.keys();
	DenseEdgeList newInstance = new DenseEdgeList();
	for (int i = 0; i < keys.length; i++) {
	    newInstance.put(keys[i], list.get(keys[i]));
	}
	return newInstance;
    }