replaced the member '_class_name' by the 'class.__name__'

chains/stop_market.py

@@ -4,8 +4,7 @@ from supermarket_chain import SupermarketChain
 
 class StopMarket(CerberusWebClient, SupermarketChain):
     _date_hour_format = '%Y-%m-%d %H:%M:%S'
-    _class_name = 'Stop_Market'
 
     @property
     def username(self):
-        return self._class_name
+        return 'Stop_Market'