old_contents: from __future__ import unicode_literals
  
  
  class Node(object):
  
      def __init__(self, value):
          self.value = value
          self.next_node = None
  
  
  class LinkedList(object):
  
      def __init__(self, iterable=None):
          self.sizeOfList = 0
          self.head = None
          self.tail = None
  
          if iterable is not None:
              for item in iterable:
                  self.insert(item)
  
      def insert(self, val):
          new_node = Node(val)
  
          if self.sizeOfList == 0:
              self.head = self.tail = new_node
              self.sizeOfList += 1
          else:
              self.tail.next_node = new_node
              self.tail = new_node
              self.sizeOfList += 1
  
      def pop(self):
          current = self.head
          previous = None
          val = self.tail.value
  
          if self.sizeOfList  == 1:
              self.head = self.tail = None
              self.sizeOfList -= 1
              return val
          else:
              while current is not self.tail:
                  previous = current
                  current = current.next_node
              self.tail = previous
              previous.next_node = None
              self.sizeOfList -= 1
              return val
  
      def size(self):
          return self.sizeOfList
  
      def display(self):
          current = self.head
          result = ()
          while current is not None:
              result += (current.value,)
              current = current.next_node
          return result
  
  
new_contents: from __future__ import unicode_literals
  
  
  class Node(object):
  
      def __init__(self, value):
          self.value = value
          self.next_node = None
  
  
  class LinkedList(object):
  
      def __init__(self, iterable=None):
          self.sizeOfList = 0
          self.head = None
  
          if iterable is not None:
              for item in iterable:
                  self.insert(item)
  
      def insert(self, val):
          new_node = Node(val)
          current = self.head
  
          if current is None:
              self.head = new_node
              self.sizeOfList += 1
          else:
              while current.next_node is not None:
                  current = current.next_node
              current.next_node = new_node
              self.sizeOfList += 1
  
  
      def pop(self):
          value = self.head.value
          self.head = self.head.next_node
          self.sizeOfList -= 1
          return value
  
      def size(self):
          return self.sizeOfList
  
      def display(self):
          current = self.head
          result = ()
          while current is not None:
              result += (current.value,)
              current = current.next_node
          return result
          
subject: add new version of queue.py and queue_linked_list.py