old_contents: class Stack(object):
      """Implementation of Stack ADT"""
  
      def __init__(self, items=[]):
          self.items = items
  
      def is_empty(self):
          return self.items == []
  
      def push(self, item):
          self.items.append(item)
  
      def pop(self):
          if not self.is_empty():
              return self.items.pop()
  
      def peek(self):
          if not self.is_empty():
              return self.items[len(self.items) - 1]
  
      def size(self):
          return len(self.items)
  
  
  class Queue(object):
      """Implementation of Queue ADT."""
  
      def __init__(self, items=[]):
          self.items = items
          self.items.reverse()
  
      def is_empty(self):
          return self.items == []
  
      def enqueue(self, item):
          self.items.insert(0, item)
  
      def dequeue(self):
          if not self.is_empty():
              return self.items.pop()
  
      def size(self):
          return len(self.items)
  
  
  class Deque(object):
      """Implementation of Deque ADT."""
  
      def __init__(self, items=[]):
          self.items = items
  
      def is_empty(self):
          return self.items == []
  
      def add_front(self, item):
          self.items.append(item)
  
      def add_rear(self, item):
          self.items.insert(0, item)
  
      def remove_front(self):
          return self.items.pop()
  
      def remove_rear(self):
          return self.items.pop(0)
  
      def size(self):
          return len(self.items)
  
new_contents: class Stack(object):
      """Implementation of Stack ADT"""
  
      def __init__(self, items=[]):
          self.items = items
  
      def is_empty(self):
          return self.items == []
  
      def push(self, item):
          self.items.append(item)
  
      def pop(self):
          if not self.is_empty():
              return self.items.pop()
  
      def peek(self):
          if not self.is_empty():
              return self.items[len(self.items) - 1]
  
      def size(self):
          return len(self.items)
  
  
  class Queue(object):
      """Implementation of Queue ADT."""
  
      def __init__(self, items=[]):
          self.items = items
          self.items.reverse()
  
      def is_empty(self):
          return self.items == []
  
      def enqueue(self, item):
          self.items.insert(0, item)
  
      def dequeue(self):
          if not self.is_empty():
              return self.items.pop()
  
      def size(self):
          return len(self.items)
  
  
  class Deque(object):
      """Implementation of Deque ADT."""
  
      def __init__(self, items=[]):
          self.items = items
  
      def is_empty(self):
          return self.items == []
  
      def add_front(self, item):
          self.items.append(item)
  
      def add_rear(self, item):
          self.items.insert(0, item)
  
      def remove_front(self):
          return self.items.pop()
  
      def remove_rear(self):
          return self.items.pop(0)
  
      def size(self):
          return len(self.items)
  
  
  class Node(object):
      """Implementation of a Node."""
  
      def __init__(self, data):
          self.data = data
          self.next = None
  
      def get_data(self):
          return self.data
  
      def set_data(self, data):
          self.data = data
  
      def get_next(self):
          return self.next
  
      def set_next(self, next):
          self.next = next
  
subject: Implement a Node