python basic graph

graph.py

class Graph(dict)
    def __init__(self, v=[], es=[])
    """create a ew graph. (vs) is a list of vertices, (es) is a list of of edges"""
    for v in vs:
        self.add_vertex(v)

    for e in es:
        self.add_edge(e)

    def add_vertex(self, v):
        """add (v) to the graph"""
        self[v] = {}

    def add_edge(self, e):
        v,w = e
        self[v][w] = e
        self[w][v]