N = closedNeighborhood(G,v)
The closed neighborhood of a vertex v just the union of the open neighborhood (or neighbors) of v and the vertex v itself
i1 : G = cycleGraph 4;
i2 : closedNeighborhood(G,2) o2 = set {1, 2, 3} o2 : Set
The object closedNeighborhood is a method function.