input: Write a function to create a linked list in Python using a class definition. The function should define a `ListNode` class with an `__init__` method that initializes the data and sets the next pointer to None. The function should return an instance of the `ListNode` class.
  assert create_linked_list(1).data == 1
  assert create_linked_list(1).next == None
  assert create_linked_list(2).data == 2
  assert create_linked_list(2).next == None
output: def create_linked_list(data):
      class ListNode:
          def __init__(self, data):
              self.data = data
              self.next = None
      return ListNode(data)