add some output

FCO/failfcopreservation

+TmTApp (TmCast (CoAll (CoAll (CoTop (TyAll (TyAll (TyVar (STypeVar Z))))))) (TmCast (CoArrow (CoBot (TyProd TyInt TyInt)) (CoTop (TyArr TyTop TyInt))) (TmAbs (TmInt 0) (TyAll (TyAll (TyVar (STypeVar Z))))))) (TyAll (TyAll (TyVar (STypeVar Z))))

FCO/out

+===Testing Preservation property for FCo===
+Testing preservation with size 4
++++ OK, passed 1000 tests; 869916 discarded.
+Time: 5.742400996 s
+Testing preservation with size 5
+*** Failed! (after 526 tests):
+Exception:
+  Prelude.undefined
+  CallStack (from HasCallStack):
+    error, called at libraries/base/GHC/Err.hs:80:14 in base:GHC.Err
+    undefined, called at Test.hs:19:60 in main:Main
+TmTApp (TmCast (CoAll (CoAll (CoTop (TyAll (TyAll (TyVar (STypeVar Z))))))) (TmCast (CoArrow (CoBot (TyProd TyInt TyInt)) (CoTop (TyArr TyTop TyInt))) (TmAbs (TmInt 0) (TyAll (TyAll (TyVar (STypeVar Z))))))) (TyAll (TyAll (TyVar (STypeVar Z))))
+Time: 18.358127853 s
+===Testing Progress property for FCo===
+Testing progress with size 4
++++ OK, passed 1000 tests; 855985 discarded.
+Time: 5.785738026 s
+Testing progress with size 5
++++ OK, passed 1000 tests; 4851947 discarded.
+Time: 33.187360357 s
+Testing progress with size 6
++++ OK, passed 1000 tests; 27524988 discarded.
+Time: 227.752253052 s
+Testing progress with size 7
++++ OK, passed 1000 tests; 634379703 discarded.
+Time: 5862.546623306 s
+