diff -r 116fa3c8584f -r 1bd800376e0c pre_marking2/docdiff_test4.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pre_marking2/docdiff_test4.scala	Wed Dec 02 01:15:14 2020 +0000
@@ -0,0 +1,9 @@
+
+import CW7a._
+
+val urban_list1 = List("a", "b", "b", "c", "d")
+val urban_list2 = List("d", "b", "d", "b", "d")
+
+assert(overlap(urban_list1, urban_list2) == 0.5384615384615384)
+assert(overlap(urban_list1, urban_list1) == 1.0)
+assert(overlap(urban_list2, urban_list2) == 1.0)