Finding the n-degree neighborhood of a node

import networkx as nx
G = nx.Graph()
G.add_edges_from([('v1','v2'),('v2','v4'),('v1','v3')])

def neighborhood(G, node, n):
    path_lengths = nx.single_source_dijkstra_path_length(G, node)
    return [node for node, length in path_lengths.iteritems()
                    if length == n]

print(neighborhood(G, 'v1', 1))
# ['v2', 'v3']
print(neighborhood(G, 'v1', 2))
# ['v4']