  
  
  class GroupChat(Chat):
  
      def add_user(self, user):  # ...
      def remove_user(self, user):  # ... 
  
  
  class Message(object):
  
      def __init__(self, message_id, message, timestamp):
 
</s> remove     def add_user(self, user_id, name, pass_hash):  # ...
    def remove_user(self, user_id):  # ...
    def add_friend_request(self, from_user_id, to_user_id):  # ...
    def approve_friend_request(self, from_user_id, to_user_id):  # ...
    def reject_friend_request(self, from_user_id, to_user_id):  # ...
 </s> add     def add_user(self, user_id, name, pass_hash):
        pass

    def remove_user(self, user_id):
        pass

    def add_friend_request(self, from_user_id, to_user_id):
        pass

    def approve_friend_request(self, from_user_id, to_user_id):
        pass

    def reject_friend_request(self, from_user_id, to_user_id):
        pass </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     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 </s> remove     def notify_call_escalated(self, call):  # ...
    def notify_call_completed(self, call):  # ...
    def dispatch_queued_call_to_newly_freed_employee(self, call, employee):  # ... </s> add  </s> remove         # ...
 </s> add         pass
    def add_user(self, user):
        pass

    def remove_user(self, user):
        pass
  
  
  class GroupChat(Chat):
  
    def add_user(self, user):
        pass

    def remove_user(self, user):
        pass
    def add_user(self, user):
        pass

    def remove_user(self, user):
        pass
  
  
  class Message(object):
  
      def __init__(self, message_id, message, timestamp):
keep keep keep keep replace replace keep keep keep keep keep
 Convert all .py files to be valid Python (#98) 
solutions/object_oriented_design/online_chat/online_chat.py