code: def subscribe(object_type: str, subscriber: str,
                callback_handler: Callable = None) -> EventQueue:
      
      key = _keys.subscribers(object_type)
      DB.remove_from_list(key, subscriber)
      DB.append_to_list(key, subscriber)
      return EventQueue(object_type, subscriber, callback_handler)
docs: Subscribe to the specified object type.
  
      Returns an EventQueue object which can be used to query events
      associated with the object type for this subscriber.
  
      Args:
          object_type (str): Object type
          subscriber (str): Subscriber name
          callback_handler (function, optional): Callback handler function.
  
      Returns:
          EventQueue, event queue object.