--- a/src/hugin_script_interface/top_five.py
+++ b/src/hugin_script_interface/top_five.py
@@ -1,3 +1,7 @@
+# since this plugin actually references members of the hsi
+# module (like, hsi.calcCtrlPointErrors below) we need to
+# import hsi to make these names known:
+
 import hsi
 
 # another demo plugin: this one will keep at most five control
@@ -9,7 +13,7 @@
     # this plugin doesn't take any extra arguments
 
     if args :
-        print 'ignoring extra arguments %s' % str(args)
+        print('ignoring extra arguments %s' % str(args))
 
     # on loading the CP errors are unknown - we have to have them
     # calculated before we can start:
@@ -44,4 +48,5 @@
     
     pano.setCtrlPoints ( cpv )
     
-    return 0+    return 0
+