diff -r 663c2a9108d1 -r 4de31fdc0d67 testing3/knight_test4.scala
--- a/testing3/knight_test4.scala	Sun Nov 01 01:21:31 2020 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,6 +0,0 @@
-import CW8a._
-
-val f_urban = (x:(Int, Int)) => if (x._1 > 3) Some(List(x)) else None
-
-assert(first(List((1,0),(2,0),(3,0),(4,0)), f_urban) == Some(List((4,0))))
-assert(first(List((1,0),(2,0),(3,0)), f_urban) == None)