             upgrade: upgrade
         )
 
-        self.content = convertible.content
+        self.content = content.content
     }
 }
    }
}

public protocol ContentConvertible {
    var content: Content { get }
}

extension ContentConvertible {
    public static func toContent(convertible: Self) -> Content {
        return convertible.content
    }
}

extension Collection where Self.Iterator.Element: ContentConvertible {
    public var contents: [Content] {
        return map(Self.Iterator.Element.toContent)
    }

    }
}

public protocol ContentInitializable {
    init(content: Content) throws
}

public protocol ContentMappable: ContentInitializable {
    static var key: String { get }
}

