how to inserting a node into a sorted doubly linked list

1class DoublyLinkedListNode:
2    def __init__(self, node_data):
3        self.data = node_data
4        self.next = None
5        self.prev = None
6
7def sortedInsert(head, data):
8    node = DoublyLinkedListNode(data)
9    if (head == None):
10        return node
11    elif (data < head.data):
12        node.next = head
13        head.prev = node
14        return node
15    else:
16        node = sortedInsert(head.next, data)
17        head.next = node 
18        node.prev = head
19        return head        
20