Binary Trees implementation in Python

binary_trees.py

class Node:
    def __init__(self):
        self.data=None
        self.left=None
        self.right=None

class LL:
    def __init__(self):
        self.root=None
        self.leaf=0

    def insert(self):
        stack = []
        data = int(input("Enter the root tree data : "))
        node = Node()
        self.root = node
        node.data=data
        stack.append(node)
        while len(stack)>0:
            child = stack.pop(0)
            leafCount=0
            leftData=int(input("enter the left child data of {} : ".format(child.data)))
            if leftData==-1:
                child.left=None
                leafCount+=1
            else:
                node = Node()
                node.data = leftData
                child.left=node
                stack.append(node)  

            rightData=int(input("enter the right child data of {} : ".format(child.data)))
            if rightData==-1:
                child.right=None
                leafCount+=1
            else:
                node = Node()
                node.data = rightData
                child.right=node
                stack.append(node)
            if leafCount==2:
                self.leaf+=1      

    def levelOrder(self):
        root = self.root 
        stack = []
        stack.append(root)
        while len(stack)>0:
            child=stack.pop(0)
            print(child.data)
            if child.left:
                stack.append(child.left)
            if child.right:
                stack.append(child.right) 

    def preOrder(self, root):
        if root:
            print(root.data)
            self.preOrder(root.left)
            self.preOrder(root.right)                              

ll = LL()
ll.insert()
ll.levelOrder()
print("Number of leaf node : ",ll.leaf)