:Class Penguin: Animal,BirdBehaviour,FishBehaviour ∇ R←NoCanFly :Implements Method BirdBehaviour.Fly R←'Although I am a bird, I cannot fly' ∇ ∇ R←LayOneEgg :Implements Method BirdBehaviour.Lay R←'I lay one egg every year' ∇ ∇ R←Croak :Implements Method BirdBehaviour.Sing R←'Croak, Croak!' ∇ ∇ R←Dive :Implements Method FishBehaviour.Swim R←'I can dive and swim like a fish' ∇ :EndClass ⍝ Penguin