class Vertex:
    def __init__(self, key):
        self.key = key
        self.neighbors = {}

    def get_neighbor(self, other):
        return self.neighbors.get(other, None)

    def set_neighbor(self, other, weight=0):
        self.neighbors[other] = weight

    def __repr__(self):
        return f"Vertex({self.key})"

    def __str__(self):
        return (
            str(self.key)
            + " connected to: "
            + str([x.key for x in self.neighbors])
        )

    def get_neighbors(self):
        return self.neighbors.keys()

    def get_key(self):
        return self.key

class Graph:
    def __init__(self):
        self.vertices = {}

    def set_vertex(self, key):
        self.vertices[key] = Vertex(key)

    def get_vertex(self, key):
        return self.vertices.get(key, None)

    def __contains__(self, key):
        return key in self.vertices

    def get_vertices(self):
        return self.vertices.keys()

    def __iter__(self):
        return iter(self.vertices.values())
       
    def add_edge(self,from_vert,to_vert,weight=0):
        if(not from_vert in self.vertices):
            self.set_vertex(from_vert)
        if(not to_vert in self.vertices):
            self.set_vertex(to_vert)
        self.vertices[from_vert].set_neighbor(Vertex(to_vert),weight)

            

g = Graph()
for i in range(6):
    g.set_vertex(i)
g.vertices
g.add_edge(0, 1, 5)
g.add_edge(0, 5, 2)
g.add_edge(1, 2, 4)
g.add_edge(2, 3, 9)
g.add_edge(3, 4, 7)
g.add_edge(3, 5, 3)
g.add_edge(4, 0, 1)
g.add_edge(5, 4, 8)
g.add_edge(5, 2, 1)
for v in g:
    for w in v.get_neighbors():
        print(f"({v.get_key()}, {w.get_key()})")