Doubly Linked Lists- Append and Prepend

class Node:
    def __init__(self, data):
        self.data = data 
        self.next = None
        self.prev = None


class DoublyLinkedList:
    def __init__(self):
        self.head = None

    def append(self, data):
        if self.head is None:
            new_node = Node(data)
            new_node.prev = None
            self.head = new_node 

        else:
            new_node = Node(data)
            cur = self.head 
            while cur.next:
                cur = cur.next 
            cur.next = new_node 
            new_node.prev = cur 
            new_node.next = None

    def prepend(self, data):
        if self.head is None:
            new_node = Node(data)
            new_node.next = self.head
            self.head = new_node

        else:
            new_node = Node(data)
            self.head.prev = new_node
            new_node.next = self.head
            self.head = new_node
    def print_list(self):
        cur = self.head 
        while cur:
            print(cur.data)
            cur = cur.next