import Foundation

extension Data {
    // Get the data value back as a certain type
    func toValue<T>() -> T {
        // Do something for a non-optional return
        return self.withUnsafeBytes { $0.pointee }
    }

    func toValue<T>() -> T? {
        // Do something for an optional return
        return nil
    }
}

let value: Int = Data().toValue()

let value: Int? = Data().toValue() // Ambiguous use of 'toValue()'