classDiagram
    class Animal {
        +name: string
        +age: int
        +makeSound()
        +move()
    }
    class Duck {
        +beakColor: string
        +swim()
        +quack()
    }
    class Fish {
        -sizeInFeet: int
        +canEat()
    }
    class Zebra {
        +isWild: boolean
        +run()
    }
    Animal <|-- Duck
    Animal <|-- Fish
    Animal <|-- Zebra
