[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-1)from plum import dispatch
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-2)
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-3)class Dog: pass
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-4)class Cat: pass
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-5)
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-6)@dispatch
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-7)def greet(a: Cat, b: Dog):
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-8)    return "Hiss!"
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-9)
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-10)@dispatch
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-11)def greet(a: Dog, b: Cat):
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-12)    return "Grrrr..."
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-13)
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-14)
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-15)# Let's try it out
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-16)cat, dog = Cat(), Dog()
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-17)
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-18)
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-19)print(greet(cat, dog))  # "Hiss!"
[](https://www.fast.ai/posts/2025-02-20-fasttransform.html#cb26-20)print(greet(dog, cat))  # Grrrr...