Filter a mixed value array by type

MixedArrayFilter.swift

protocol Token {
    var isSomething: Bool {get}
}

struct BasicToken : Token {
    let isSomething: Bool
}

struct FancyToken : Token {
    let isSomething: Bool
    let howFancy: Int
}

let tokens: [Token] = [
    BasicToken(isSomething: true),
    BasicToken(isSomething: false),
    FancyToken(isSomething: true, howFancy: 3),
    BasicToken(isSomething: false),
    FancyToken(isSomething: true, howFancy: 10)
]


for case let fancy as FancyToken in tokens {
    print(fancy.howFancy)
}