Can't do that:

```dart
	Test failed: Caught type 'bool' is not a subtype of type 'void' of 'function result'. null
	ORIGINAL STACKTRACE:
	 #0      NgMessage.multiple= (package:angular/directive/ng_message.dart:72:31)
	#1      _LocalInstanceMirror._invokeSetter (dart:mirrors-patch/mirrors_impl.dart:446)
```