--- /dev/null
+// circular test cases
+//testcase {
+// input "x";
+// output "a:{x}";
+//
+// s = a1:: a
+// a = s1:: s
+// a = ^"x"
+//}
+//
+//testcase {
+// input "x";
+// output "x";
+// output "s2:{s2:{s0 s0} x}";
+// output "s2:{s0 x}";
+//
+//
+// s = s2:: s s
+// s = ^"x"
+// s = s0:: ()
+//}