Linked list within a linked list

im completely stuck on how to make a linked list within a linked list.

i know how to create a linked list:

A linked list class
class SingleSortedLinkedList :
#constructor
def __init__ (self) :
self._size = 0
self._head = None

#check for empty list
def isEmpty(self) :
return self._size == 0

#overloaded length
def __len__(self) :
return self._size

#prints out the data
def traversal(self) :
current = self._head
while current is not None :
print (current._data)
current = current._next

#insets (sorted) a new data item into the list
def insert(self, item) :
newNode = ListNode(item)
self._size=self._size+1
#when our list is new (or reduced to no items)
if self._head is None :
self._head = newNode
#If our new node goes first:
elif item < self._head._data :
newNode._next = self._head
self._head = newNode
#not at the head, so we will be inserting later into the list 
else: 
node = self._head
#loop to advance pointer until insertion spot located
while node is not None and node._data < item :
prev = node
node = node._next
if node is None:
#at end, so newNode already points to None like it should.
prev._next=newNode
else:
#otherwise, update the node
prev._next=newNode
newNode._next=node




#class for a single node 
class ListNode :
def __init__ ( self, data) :
self._data = data
self._next = None

just don't know how to modify it so each node points to a separate linked list