How to print whole parent - node - child structure

Question

I want to show everything that is connected to specific node with print function but so far I can't avoid using global to do so. How can I make my __repr__function cleaner and more local? Whole code that I got so far below:

current_parent = None
indent_increase = 1


class Node(object):
    def __init__(self, data):
        self.data = data
        self.parent = None
        self.children = []

    def add_child(self, obj):
        self.children.append(obj)
        obj.parent = self.data

    def __repr__(self):
        global current_parent
        global indent_increase

        if self.children:
            print_data = ""
            print_data += "Node " + str(self.data) + " ↴" + "\n"
            indent = "    "

            for child in self.children:
                if current_parent != child.parent:
                    current_parent = child.parent
                    indent_increase += 1
                    print_data += ((indent * indent_increase) + str(child) + "\n")
                else:
                    print_data += ((indent * indent_increase) + str(child) + "\n")

            indent_increase = 1
            current_parent = 0
            return print_data
        else:
            return "Node " + str(self.data)


a = Node(1)
b = Node(2)
c = Node(3)
d = Node(4)
e = Node(5)

c.add_child(d)

a.add_child(b)
a.add_child(c)
a.add_child(e)

print(a)

Desired output:

Node 1 ↴
    Node 2
    Node 3 ↴
        Node 4
    Node 5

Answer 1

You can work without globals - you just need to split the result from nested nodes into lines and indent each of them before returning the result:

class Node(object):
    def __init__(self, data):
        self.data = data
        self.parent = None
        self.children = []

    def add_child(self, obj):
        self.children.append(obj)
        obj.parent = self

    def __repr__(self):
        if self.children:
            print_data = "Node " + repr(self.data) + " ↴" + "\n"
            indent = "    "
            for child in self.children:
              for line in repr(child).splitlines():
                print_data += indent + line + "\n"
            return print_data
        else:
            return "Node " + repr(self.data)

I made an example with more nested Nodes at https://repl.it/repls/ZanyKlutzyBase