input: Write a function to create a linked list in Python using a class. The function should be able to initialize a ListNode with data and set the next pointer to None.
  class ListNode:
      def __init__(self, data):
          self.data = data
          self.next = None
  assert ListNode(5).data == 5
  assert ListNode(5).next == None
  assert ListNode("example").data == "example"
  assert ListNode("example").next == None
  assert ListNode([1, 2, 3]).data == [1, 2, 3]
  assert ListNode([1, 2, 3]).next == None
output: def __init__(self, data):
      self.data = data
      self.next = None