class BinaryTree:
    def __init__(self,root):
        self.key = root
        self.left_child = None
        self.right_child = None
    def insert_left(self,new_node):
        if self.left_child == None:
            self.left_child = BinaryTree(new_node)
        else:
            t = BinaryTree(new_node)
            t.left_child = self.left_child
            self.left_child = t
    def insert_right(self,new_node):
        if self.right_child == None:
            self.right_child = BinaryTree(new_node)
        else:
            t = BinaryTree(new_node)
            t.right_child = self.right_child
            self.right_child = t
    def get_right_child(self):
        return self.right_child
    def get_left_child(self):
        return self.left_child
    def set_root_val(self,obj):
        self.key = obj
    def get_root_val(self):
        return self.key
    def postorder(self):
        if self != None:
            if self.get_left_child() != None:
                self.get_left_child().postorder()
            if self.get_right_child() != None:
                self.get_right_child().postorder()
                print(self.get_root_val())
    def __repr__(self):
        return "BinaryTree,Key is " + self.key
