class Node:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None
    def insert(self , value):
        current = self
        previous = None
        while current:
            if current.value > value:
                previous = current
                current = current.left
            else:
                previous = current
                current = current.right
        if previous.value > value:
            previous.left = Node(value)
        else:
            previous.right = Node(value)

    def in_order_traversal(self):
        current = self
        stack = list()
        while current or len(stack):
            if current:
                stack.append(current)
                current = current.left
            else:
                current = stack.pop()
                print(current.value)
                current = current.right
    def print(self):
        self.in_order_traversal()

t = Node(1)
t.insert(43)
t.insert(55)
t.insert(18)
t.insert(25)
t.insert(13)
t.insert(3)
t.insert(60)
t.print()