list_of_nodes = list()
list_of_edges = list()

class node:
    def __init__(self, name=""):
         self.name = name
         
    def get_name(self):
        return self.name
    
    def set_name(self, new_name=""):
        if new_name != self.name:
            old_name = self.name
            self.name = new_name
            print("name of node {} changed to {}".format(old_name, new_name))
        else:
            pass
         
n1 = node("A")
n2 = node("B")
n3 = node("C")

for n in [n1,n2,n3]:
    list_of_nodes.append(n)

print(list_of_nodes)

for n in list_of_nodes:
    print(n.get_name())

list_of_node_names = [x.get_name() for x in list_of_nodes]

print(list_of_node_names)


class edge:
    def __init__(self, nstart, nend):
        self.nstart = nstart
        self.nend = nend
    
    def __str__(self):
        s = self.nstart.get_name()
        e = self.nend.get_name()
        return "{} -> {}".format(s,e)

e1 = edge(n1, n2)
print(e1)