% TODO (unimplemented)

TYPE Animal IS INTERFACE
    FUNCTION make_sound(self: Animal)
END INTERFACE

TYPE Dog IS CLASS(Animal)
    size: Number
END CLASS

FUNCTION Dog.make_sound(self: Dog)
    print("bark \(self.size)")
END FUNCTION

TYPE Cat IS CLASS(Animal)
    longhair: Boolean
END CLASS

FUNCTION Cat.make_sound(self: Cat)
    print("meow \(self.longhair)")
END FUNCTION

VAR d: Dog
d.size := 5
VAR a: Animal := d
a.make_sound()
%= bark 5

VAR c: Cat
c.longhair := TRUE
a := c
a.make_sound()
%= meow TRUE