old_contents: """Double Linked List implementation."""
  
  
  class Node(object):
      """Make new data node."""
  
      def __init__(self, data=None, next_item=None, prev_item=None):
          """Initialize Node class with arguments."""
          self.data = data
          self.next_item = next_item
          self.prev_item = prev_item
  
  
  class DoubleLinkedList(object):
      """DoubleLinkedList class."""
  
      def __init__(self, data=None):
          """Initialize DoubleLinkedList class with arguments."""
          self.data = data
          self.head = None
          self.tail = None
          self.size = 0
  
new_contents: """Double Linked List implementation."""
  
  
  class Node(object):
      """Make new data node."""
  
      def __init__(self, data=None, next_item=None, prev_item=None):
          """Initialize Node class with arguments."""
          self.data = data
          self.next_item = next_item
          self.prev_item = prev_item
  
  
  class DoubleLinkedList(object):
      """DoubleLinkedList class."""
  
      def __init__(self, data=None):
          """Initialize DoubleLinkedList class with arguments."""
          self.data = data
          self.head = None
          self.tail = None
          self.size = 0
  
      def push(self, val):
          """Push a node in initialized Double Linked List."""
          new_node = Node(val, next_item=self.head)
          self.head = new_node
          self.size += 1
  
subject: add push method to DoubleLinkedList class