(self, model_class=None)
Override this to be notified when tracked models have been cleared.
        :param model_class: May be None which indicates that all types have been cleared.
Override this to be notified when tracked models have been cleared.
        :param model_class: May be None which indicates that all types have been cleared.
Override this to be notified when tracked models have been cleared . : param model_class : May be None which indicates that all types have been cleared .
def on_tracked_models_cleared(self, model_class=None):
        """
        Override this to be notified when tracked models have been cleared.
        :param model_class: May be None which indicates that all types have been cleared.
        """
        pass
def on_tracked_models_cleared ( self , model_class = None ) : pass