Python Doubly Linked List - Inserts data into a new node after the given node -

i writing code doubly linked list in python. however, struggling how insert data new node after given node. , understanding wrong constructing doubly linked list's insertafter() method in python. want know how fix code.

this code far:

class node:       # constructor initialize data    # if data not given user,its taken none      def __init__(self, data=none, next=none, prev=none):         self.data = data         self.next = next         self.prev = prev  class doubly_linked_list:     def __init__(self):         self.head = none         self.tail = none      #  inserts data new node after given node     def insertafter(self, node, data):         runner = node(none, data, node, none)         runner.next = self.head         if self.head not none:             self.head.prev = runner         self.head = runner      # # adds given value last value in list     def addlast(self, data):         if self.head not none:             runner = self.head             while(runner.next != none):                 runner = runner.next             runner.next = node(data, none, runner)             self.tail = runner.next         else:             self.head = node(data)             self.tail = self.head      def print_next_list(self): # traverse forwards         runner = self.head         while (runner not none):             print(runner.data)              runner = runner.next      def print_prev_list(self): # traverse backwards         runner = self.tail         while (runner not none):             print(runner.data)             runner = runner.prev  # initializing list alist = doubly_linked_list()  alist.addlast(3) alist.addlast(5) alist.addlast(7) alist.addlast(9) alist.addlast(11)  alist.print_next_list() print() alist.print_prev_list()  alist.insertafter(5,7) #this shows me error. 

i have no idea doing in:

def insertafter(self, node, data):     runner = node(none, data, node, none)     runner.next = self.head     if self.head not none:         self.head.prev = runner     self.head = runner 

this should be:

def insertafter(self, node, data):     newnode = node(data, node.next, node)     node.next = newnode 

here create new node data passed , place after passed node.