--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core_testing2/docdiff_test3.scala	Mon Nov 08 01:03:09 2021 +0000
@@ -0,0 +1,11 @@
+
+import C2._
+
+val urban_list1 = List("a", "b", "b", "c", "d")
+val urban_list2 = List("d", "b", "d", "b", "d")
+
+assert(prod(urban_list1, urban_list2) == 7)
+
+assert(prod(urban_list1, urban_list1) == 7)
+
+assert(prod(urban_list2, urban_list2) == 13)