--- a/util/set.lua	Thu Apr 06 16:27:37 2023 +0200
+++ b/util/set.lua	Thu Apr 06 16:30:26 2023 +0200
@@ -186,7 +186,7 @@
 	for item in pairs(items) do
 		s[#s+1] = tostring(item);
 	end
-	return t_concat(s, ", ");
+	return "{"..t_concat(s, ", ").."}";
 end
 
 function set_mt.__freeze(set)