diff -r ed1b6b8c36e5 -r 0b727d1a8184 main_testing3/re_test1.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main_testing3/re_test1.scala	Mon Nov 02 02:31:44 2020 +0000
@@ -0,0 +1,11 @@
+import CW8c._
+
+assert(nullable(ZERO) == false)
+assert(nullable(ONE) == true)
+assert(nullable(CHAR('a')) == false)
+assert(nullable(ZERO | ONE) == true)
+assert(nullable(ZERO | CHAR('a')) == false)
+assert(nullable(ONE ~  ONE) == true)
+assert(nullable(ONE ~ CHAR('a')) == false)
+assert(nullable(STAR(ZERO)) == true)
+