diff --git a/ostap/histos/tests/test_histos_roc.py b/ostap/histos/tests/test_histos_roc.py
index 36000390..a90bb96e 100644
--- a/ostap/histos/tests/test_histos_roc.py
+++ b/ostap/histos/tests/test_histos_roc.py
@@ -31,7 +31,6 @@
 logger.info ( "Test for `roc_curve'")
 # =============================================================================
 
-
 # =============================================================================
 def test_roc () :