def degreeSequence(self):
        """
           degree sequence is the reverse sorder of the vertices degrees
           Isomorphic graphs have the same degree sequence. However,
           two graphs with the same degree sequence are not necessarily
           isomorphic.
           More-Info:
           http://en.wikipedia.org/wiki/Graph_realization_problem
        """
        seq = []
        for vertex in self.v:
            seq.append(self.getDegree(vertex))
        seq.sort(reverse=True)
        return tuple(seq)

           degree sequence is the reverse sorder of the vertices degrees
           Isomorphic graphs have the same degree sequence. However,
           two graphs with the same degree sequence are not necessarily
           isomorphic.
           More-Info:
           http://en.wikipedia.org/wiki/Graph_realization_problem
        
recipes/Python/579141_Simple_Graph_library/recipe-579141.py