diff -r 244df77507c2 -r 253d1ccb65de core_marking3/postfix_test4.scala
--- a/core_marking3/postfix_test4.scala	Sun Sep 15 12:57:59 2024 +0100
+++ b/core_marking3/postfix_test4.scala	Mon Jul 21 16:38:07 2025 +0100
@@ -1,13 +1,16 @@
-import C3b._
+
+def urbanmain() = {
+  import C3b._
 
 
-assert(compute(syard(split("3 + 4 * ( 2 - 1 )"))) == 7)
-assert(compute(syard(split("10 + 12 * 33"))) == 406)
-assert(compute(syard(split("( 5 + 7 ) * 2"))) == 24)
-assert(compute(syard(split("5 + 7 / 2"))) == 8)
-assert(compute(syard(split("5 * 7 / 2"))) == 17)
-assert(compute(syard(split("9 + 24 / ( 7 - 3 )"))) == 15)
-assert(compute(syard(split("4 ^ 3 ^ 2"))) == 262144)
-assert(compute(syard(split("4 ^ ( 3 ^ 2 )"))) == 262144)
-assert(compute(syard(split("( 4 ^ 3 ) ^ 2"))) == 4096)
-assert(compute(syard(split("( 3 + 1 ) ^ 2 ^ 3"))) == 65536)
+  assert(compute(syard(split("3 + 4 * ( 2 - 1 )"))) == 7)
+  assert(compute(syard(split("10 + 12 * 33"))) == 406)
+  assert(compute(syard(split("( 5 + 7 ) * 2"))) == 24)
+  assert(compute(syard(split("5 + 7 / 2"))) == 8)
+  assert(compute(syard(split("5 * 7 / 2"))) == 17)
+  assert(compute(syard(split("9 + 24 / ( 7 - 3 )"))) == 15)
+  assert(compute(syard(split("4 ^ 3 ^ 2"))) == 262144)
+  assert(compute(syard(split("4 ^ ( 3 ^ 2 )"))) == 262144)
+  assert(compute(syard(split("( 4 ^ 3 ) ^ 2"))) == 4096)
+  assert(compute(syard(split("( 3 + 1 ) ^ 2 ^ 3"))) == 65536)
+}