diff -r a057dc4457fc -r 87b9e3e2c1a7 marking/re2b_test.scala
--- a/marking/re2b_test.scala	Tue Oct 29 11:11:44 2019 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,56 +0,0 @@
-import scala.concurrent._
-import scala.concurrent.duration._
-import ExecutionContext.Implicits.global
-import scala.language.postfixOps 
-
-val EVIL_urban = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))
-
-def nullable_urban (r: Rexp) : Boolean = r match {
-  case ZERO => false
-  case ONE => true
-  case CHAR(_) => false
-  case ALT(r1, r2) => nullable_urban(r1) || nullable_urban(r2)
-  case SEQ(r1, r2) => nullable_urban(r1) && nullable_urban(r2)
-  case STAR(_) => true
-}
-
-def der_urban (c: Char, r: Rexp) : Rexp = r match {
-  case ZERO => ZERO
-  case ONE => ZERO
-  case CHAR(d) => if (c == d) ONE else ZERO
-  case ALT(r1, r2) => ALT(der_urban(c, r1), der_urban(c, r2))
-  case SEQ(r1, r2) => 
-    if (nullable_urban(r1)) ALT(SEQ(der_urban(c, r1), r2), der_urban(c, r2))
-    else SEQ(der_urban(c, r1), r2)
-  case STAR(r1) => SEQ(der_urban(c, r1), STAR(r1))
-}
-
-def simp_urban(r: Rexp) : Rexp = r match {
-  case ALT(r1, r2) => (simp_urban(r1), simp_urban(r2)) match {
-    case (ZERO, r2s) => r2s
-    case (r1s, ZERO) => r1s
-    case (r1s, r2s) => if (r1s == r2s) r1s else ALT (r1s, r2s)
-  }
-  case SEQ(r1, r2) =>  (simp_urban(r1), simp_urban(r2)) match {
-    case (ZERO, _) => ZERO
-    case (_, ZERO) => ZERO
-    case (ONE, r2s) => r2s
-    case (r1s, ONE) => r1s
-    case (r1s, r2s) => SEQ(r1s, r2s)
-  }
-  case r => r
-}
-
-import scala.annotation.tailrec
-
-@tailrec
-def iterT_urban[A](n: Int, f: A => A, x: A): A = 
-  if (n == 0) x else iterT_urban(n - 1, f, f(x)) 
-
-
-lazy val f = Future {
-  assert(size(iterT_urban(20, (r: Rexp) => der_urban('a', r), EVIL_urban)) == 7340068) 
-  assert(size(iterT_urban(20, (r: Rexp) => simp_urban(der_urban('a', r)), EVIL_urban)) == 8) 
-}
-
-Await.result(f, 90 second)