code: def dispatch(self, receiver):
          ''' Dispatch handling of this event to a receiver.
  
          This method will invoke ``receiver._session_callback_added`` if
          it exists.
  
          '''
          super(SessionCallbackAdded, self).dispatch(receiver)
          if hasattr(receiver, '_session_callback_added'):
              receiver._session_callback_added(selff dispatch(self, receiver):
          ''' Dispatch handling of this event to a receiver.
  
          This method will invoke ``receiver._session_callback_added`` if
          it exists.
  
          '''
          super(SessionCallbackAdded, self).dispatch(receiver)
          if hasattr(receiver, '_session_callback_added'):
              receiver._session_callback_added(self)
docs: Dispatch handling of this event to a receiver.
  
          This method will invoke ``receiver._session_callback_added`` if
          it exists.