diff -r 244df77507c2 -r 253d1ccb65de core_marking1/collatz_test2.scala
--- a/core_marking1/collatz_test2.scala	Sun Sep 15 12:57:59 2024 +0100
+++ b/core_marking1/collatz_test2.scala	Mon Jul 21 16:38:07 2025 +0100
@@ -1,10 +1,12 @@
-import C1._
-
-assert(collatz_max(10) == (19, 9))
-assert(collatz_max(100) == (118, 97))
-assert(collatz_max(1000) == (178, 871))
-assert(collatz_max(10000) == (261, 6171))
-assert(collatz_max(100000) == (350, 77031))
-assert(collatz_max(1000000) == (524, 837799))
-assert(collatz_max(2) == (1, 2))
-assert(collatz_max(77000) == (339, 52527))
+def urbanmain() = {
+  import C1._
+ 
+  assert(collatz_max(10) == (19, 9))
+  assert(collatz_max(100) == (118, 97))
+  assert(collatz_max(1000) == (178, 871))
+  assert(collatz_max(10000) == (261, 6171))
+  assert(collatz_max(100000) == (350, 77031))
+  assert(collatz_max(1000000) == (524, 837799))
+  assert(collatz_max(2) == (1, 2))
+  assert(collatz_max(77000) == (339, 52527))
+}