tweaks

csst_common/data_manager.py

@@ -274,7 +274,8 @@ class CsstMbiDataManager:
         return fp
 
     @staticmethod
-    def __testddl__(self):
+    def __testddl__():
+        """ test function """
         dm = CsstMbiDataManager(
             ver_sim="C5.2",
             dir_l0="/nfsdata/share/csst_simulation_data/Cycle-5-SimuData/multipleBandsImaging"