input: Write a function to create a class representing a linked list node in Python. The class should have an initializer that accepts data to be stored in the node and an attribute for the next node. The next node should be initially set to None.
  assert ListNode(10).data==10
  assert ListNode(10).next==None
output: class ListNode:
      def __init__(self, data):
          self.data = data
          self.next = None