enum Team {
    case Blue
    case Red
    case Neutral
}

struct Character {
    let name: String
      , level: Int
      , hp: Float
      , mp: Float
      , attackPower: Float
      , magicPower: Float
      , owner: Team

    func attack (victim: Character) -> Character {
        return Character (
            victim,
            hp: victim.hp - attackPower // The Sole difference
        )
    }

    init (
        _ s: Character,
        name: String? = nil,
        level: Int? = nil,
        hp: Float? = nil,
        mp: Float? = nil,
        attackPower: Float? = nil,
        magicPower: Float? = nil,
        owner: Team? = nil
    ) {
        self.name = name ?? s.name
        self.level = level ?? s.level
        self.hp = hp ?? s.hp
        self.mp = mp ?? s.mp
        self.attackPower = attackPower ?? s.attackPower
        self.magicPower = magicPower ?? s.magicPower
        self.owner = owner ?? s.owner
    }
}