diff --git a/examples/how_this_code_will_be_used.py b/examples/how_this_code_will_be_used.py
index bccbf390be631d14820ef4ca0d0cf8723db5207c..b4e8f27418ba1da068de1a5115e96c4b107cd0c6 100644
--- a/examples/how_this_code_will_be_used.py
+++ b/examples/how_this_code_will_be_used.py
@@ -49,10 +49,19 @@ class CsstProcFlipImage(CsstProcessor):
         return
 
     @staticmethod
-    def run_one_detector(dm, ccd_id):
+    def run_one_detector(dm: CsstMscDataManager, ccd_id: int = 6):
         """ run for one detector
 
-        this function
+        Parameters
+        ----------
+        dm:
+            csst data manager, used to manage the input/output file paths
+        ccd_id:
+            detector id
+
+        Returns
+        -------
+        the flipped image
         """
         # input file path
         fp_input = dm.l1_ccd(ccd_id, post="img.fits")