diff -r 244df77507c2 -r 253d1ccb65de core_marking3/postfix_test1.scala
--- a/core_marking3/postfix_test1.scala	Sun Sep 15 12:57:59 2024 +0100
+++ b/core_marking3/postfix_test1.scala	Mon Jul 21 16:38:07 2025 +0100
@@ -1,7 +1,10 @@
-import C3a._
 
 
-assert(syard(split("3 + 4 * ( 2 - 1 )")) == List("3", "4", "2", "1", "-", "*", "+"))
-assert(syard(split("( ( ( 3 ) ) + ( ( 4 + ( 5 ) ) ) )")) == List("3", "4", "5", "+", "+"))
-assert(syard(split("5 + 7 / 2")) == List("5", "7", "2", "/", "+"))
-assert(syard(split("5 * 7 / 2")) == List("5", "7", "*", "2", "/"))
+def urbanmain() = {
+  import C3a._
+
+  assert(syard(split("3 + 4 * ( 2 - 1 )")) == List("3", "4", "2", "1", "-", "*", "+"))
+  assert(syard(split("( ( ( 3 ) ) + ( ( 4 + ( 5 ) ) ) )")) == List("3", "4", "5", "+", "+"))
+  assert(syard(split("5 + 7 / 2")) == List("5", "7", "2", "/", "+"))
+  assert(syard(split("5 * 7 / 2")) == List("5", "7", "*", "2", "/"))
+}