diff --git a/test_preprocess.py b/test_preprocess.py
index 91a1350..dfae109 100644
--- a/test_preprocess.py
+++ b/test_preprocess.py
@@ -3,6 +3,7 @@
 
 import preprocess
 
+# the following is list of tests
 
 def test_center():
     # After centering, mean should be the desired mean and the