old_contents: class LinkedList(object):
      def __init__(self, head=None):
          self.head = head
  
  
  class Node(object):
      def __init__(self, val, next):
          self.val = val
          self.next = next
  
new_contents: """Module defining linked list."""
  
  
  class LinkedList(object):
      """Classic linked list data structure."""
  
      def __init__(self, head=None):
          """Initialize LinkedList instance."""
          self.head = head
  
      def push(self, val):
          """Insert val at the head of linked list."""
          self.head = Node(val, self.head)
  
  
  class Node(object):
      """Node class."""
  
      def __init__(self, val, next):
          """Initialize Node instance."""
          self.val = val
          self.next = next
  
subject: define linked list push method