diff -r 3f34da7a3094 -r 12dc251fc47e testing3/knight_test4.scala
--- a/testing3/knight_test4.scala	Thu Oct 31 09:49:33 2019 +0000
+++ b/testing3/knight_test4.scala	Thu Oct 31 10:44:10 2019 +0000
@@ -1,3 +1,4 @@
+import CW8a._
 
 val f_urban = (x:(Int, Int)) => if (x._1 > 3) Some(List(x)) else None