text: class Stack:
      def __init__(self):
          self.items = []
  
      def size(self):
          return len(self.items)
  
      def push(self, item):
          self.items.append(item)
  
      def pop(self):
          if self.size() == 0:
              return None
          return self.items.pop()
  
  def test():
      MyStack = Stack()
  
      MyStack.push("Web Page 1")
      MyStack.push("Web Page 2")
      MyStack.push("Web Page 3")
  
      print (MyStack.items)
  
      MyStack.pop()
      MyStack.pop()
  
      print ("Pass" if (MyStack.items[0] == 'Web Page 1') else "Fail")
  
      MyStack.pop()
  
      print ("Pass" if (MyStack.pop() == None) else "Fail")
  