text: class DoublyLinkedListNode(object):
      def __init__(self, value):
          self.value = value
          self.prev_node = None
          self.next_node = None
  
  
  a = DoublyLinkedListNode(1)
  b = DoublyLinkedListNode(2)
  c = DoublyLinkedListNode(3)
  
  a.next_node = b
  b.prev_node = a
  
  b.next_node = c
  c.prev_node = b
  
  