Adding Nodes to a graph displays object instead of string (adjacency list)

I'm learning how to create a graph using an adjacency list on Python. My current problem is when trying to add a node to the list, it displays the Node object at 0x0000.... instead of a string. When I try to print out the list, I get TypeError: list indices must be integers or slices, not Node". I can't seem to figure out a way to fix this. Any help would be appreciated!

class Node:
    def __init__(self, name):
        self.name = name
        self.visited = False
        self.adjacency = []

    def addNeighbor(self, v):
        if v not in self.adjacency:
            self.adjacency.append(v)


class DGraph:
    def __init__(self, size=20):
        self.size = size
        self.numNodes = 0
        self.nodeList = [0] * size

    def addNode(self, name):
        """adds new node to graph"""
        if self.numNodes >= self.size:
            raise OverflowError("Graph Size Exceeded")
        newNode = Node(name)
        newNode.name = name
        newNode.addNeighbor(name)
        self.nodeList[self.numNodes] = newNode
        self.numNodes += 1

    def listNodes(self):
        theList = "Nodes: "
        for i in self.nodeList:
            theList += self.nodeList[i]
            theList += ""
        return theList


tree = DGraph()
tree.addNode("A")
tree.addNode('C')
tree.addNode('T')

What the list looks like in the debugger

You can specify string representation of your object by implementing __repr__ See details in the docs and this question Here is a working example (nodeList is fixed too)

class Node:
    def __init__(self, name):
        self.name = name
        self.visited = False
        self.adjacency = []

    def addNeighbor(self, v):
        if v not in self.adjacency:
            self.adjacency.append(v)

    def __repr__(self):
        return self.name

    def __str__(self):
        return self.name



class DGraph:
    def __init__(self, size=20):
        self.size = size
        self.numNodes = 0
        self.nodeList = [0] * size

    def addNode(self, name):
        """adds new node to graph"""
        if self.numNodes >= self.size:
            raise OverflowError("Graph Size Exceeded")
        newNode = Node(name)
        newNode.name = name
        newNode.addNeighbor(name)
        self.nodeList[self.numNodes] = newNode
        self.numNodes += 1

    def listNodes(self):
        theList = "Nodes: "
        for i in self.nodeList:
            theList += str(i)
            theList += " "
        return theList


tree = DGraph()
tree.addNode("A")
tree.addNode('C')
tree.addNode('T')
print(tree.listNodes())

Now debugger will show node names (using__repr__)

Such implementation of __repr__ is probably not a good idea unless you enforce uniqueness of node names.

As a side note, it's nice to follow naming convention in Python