code: def _on_change(self, obj, old, value, **kwargs):
          
          kwargs['property'] = self
          obj.emit(self.name, obj, value, old=old, **kwargs)
docs: Called internally to emit changes from the instance object
  
          The keyword arguments here will be passed to callbacks through the
          instance object's :meth:`~pydispatch.dispatch.Dispatcher.emit` method.
  
          Keyword Args:
              property: The :class:`Property` instance. This is useful if multiple
                  properties are bound to the same callback. The attribute name
              keys (optional): If the :class:`Property` is a container type
                  (:class:`ListProperty` or :class:`DictProperty`), the changes
                  may be found here.
                  This is not implemented for nested containers and will only be
                  available for operations that do not alter the size of the
                  container.