Challenge: Flattening nested optionals

Using Swift
3

Another try:

private protocol _OptionalProtocol {
    var _deepUnwrapped: Any? { get }
}
extension Optional: _OptionalProtocol {
    fileprivate var _deepUnwrapped: Any? {
        if let wrapped = self { return deepUnwrap(wrapped) }
        return nil
    }
}
func deepUnwrap(_ any: Any) -> Any? {
    if let optional = any as? _OptionalProtocol {
        return optional._deepUnwrapped
    }
    return any
}

deepUnwrap(1)                                                       // 1
deepUnwrap(Optional<Int>.none)                                      // nil
deepUnwrap(Optional<Int>.some(1))                                   // 1
deepUnwrap(Optional<Optional<Int>>.none)                            // nil
deepUnwrap(Optional<Optional<Int>>.some(Optional<Int>.none))        // nil
deepUnwrap(Optional<Optional<Int>>.some(Optional<Int>.some(1)))     // 1
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