class Human : IAnimal by Animal(), HandAble by Hand(), FootAble by Foot()
class Cat : IAnimal by Animal(), FootAble by Foot()

interface IAnimal {
    var head: String?
    var heart: String?
}

interface FootAble {
    var foot: String?
}

interface HandAble {
    var hand: String?
}

class Animal : IAnimal {
    override var head: String? = null
    override var heart: String? = null
}

class Foot : FootAble {
    override var foot: String? = null
}

class Hand : HandAble {
    override var hand: String? = null
}