input: Write a function to implement a linked list creation in Python using a custom class. The function should create a linked list node class. The function should be named `ListNode` with an `__init__` constructor that accepts `data` as an argument and sets the `next` attribute to `None`.
  
  class ListNode:
      def __init__(self, data):
          self.data = data
          self.next = None
output: class ListNode:
      def __init__(self, data):
          self.data = data
          self.next = None