def trivial_graph(create_using=None):
 G = empty_graph(1, create_using)
 G.name = 'trivial_graph()'
 return G

def trivial_graph ( create_using = None ) : G = empty_graph ( 1 , create_using ) G . name = 'trivial_graph()' return G
return the trivial graph with one node and no edges .