class Node:
    def __init__(self, value, left=None, right=None):
        self.left = left
        self.right = right
        self.value = value
        pass


class Tree:
    def __init__(self):
        self.root = None
        pass

    def createNode(self, val):
        return Node(val)

    def insert(self, value):
        self.__insert(self.root, value)

    def __insert(self, rootptr, val):
        if rootptr is None:
            rootptr = self.createNode(val)
            return 0

        elif val < rootptr.value:
            if rootptr.left is not None:
                self.__insert(rootptr.left, val)
            else:
                rootptr.left = self.createNode(val)

        elif val > rootptr.value:
            if rootptr.right is not None:
                self.__insert(rootptr.right, val)
            else:
                rootptr.right = self.createNode(val)

        else:
            #TODO: raise exception
            print("Duplicate value!")



    def traversePreorder(self):
        self.__traversePreorder(self.root)

    def __traversePreorder(self, rootptr):
        if rootptr is None:
            return 1
        print(rootptr.value)
        self.__traversePreorder(rootptr.left)
        self.__traversePreorder(rootptr.right)




mytree = Tree()
mytree.insert(1)
mytree.insert(2)
mytree.insert(2)
mytree.insert(4)
mytree.insert(5)
mytree.traversePreorder()