  
      UNREAD = 0
      READ = 1
      ACCEPTED = 2
      REJECTED = 3 
</s> remove             self.lookup[query] = new_node </s> add  </s> remove     def move_to_front(self, node):  # ...
    def append_to_front(self, node):  # ...
    def remove_from_tail(self):  # ...
 </s> add     def move_to_front(self, node):
        pass

    def append_to_front(self, node):
        pass

    def remove_from_tail(self):
        pass </s> remove         ...
 </s> add         pass </s> remove         ...
 </s> add         pass </s> remove     def message_user(self, friend_id, message):  # ...
    def message_group(self, group_id, message):  # ...
    def send_friend_request(self, friend_id):  # ...
    def receive_friend_request(self, friend_id):  # ...
    def approve_friend_request(self, friend_id):  # ...
    def reject_friend_request(self, friend_id):  # ...
 </s> add     def message_user(self, friend_id, message):
        pass

    def message_group(self, group_id, message):
        pass

    def send_friend_request(self, friend_id):
        pass

    def receive_friend_request(self, friend_id):
        pass

    def approve_friend_request(self, friend_id):
        pass

    def reject_friend_request(self, friend_id):
        pass
  
      UNREAD = 0
      READ = 1
      ACCEPTED = 2

keep keep keep keep replace
 Convert all .py files to be valid Python (#98) 
solutions/object_oriented_design/online_chat/online_chat.py