--- a/marking4/re_test1.scala	Wed Oct 30 12:47:10 2019 +0000
+++ b/marking4/re_test1.scala	Wed Oct 30 14:07:58 2019 +0000
@@ -1,3 +1,4 @@
+import CW9c._
 
 assert(nullable(ZERO) == false)
 assert(nullable(ONE) == true)