toDatum (ExerciseListenedQuestion c q a) = ListenedQuestion <$> decode c <*> decode q <*> decode a
toDatum (ExerciseListenedQuestion c q a) = ListenedQuestion <$> decode c <*> decode q <*> decode a
toDatum (ExerciseListenedQuestion c q a) = ListenedQuestion <$> decode c <*> decode q <*> decode a