```ucm:hide
scratch/main> builtins.merge
```

```unison
debug a = match Debug.toText a with
  None -> ""
  Some (Left a) -> a
  Some (Right a) -> a

test> t1 = if bool then [Ok "Yay"] 
           else [Fail (debug [1,2,3])]
bool = true

allowDebug = debug [1,2,3]
```

```ucm
scratch/main> add
scratch/main> test
```

```unison
bool = false
```

```ucm:error
scratch/main> update.old
scratch/main> test
```