Swift编译器错误表达式列表中的预期表达式

Question

使用swift语法时出错：

public func successor() -> JSONIndex {
    switch self.type {
    case .array:
        return JSONIndex(arrayIndex: (self.arrayIndex! + 1))
    case .dictionary:
        return JSONIndex(dictionaryIndex: <#T##Dictionary corresponding to your index##Dictionary<<#Key: Hashable#> Any>#>.index(after: self.dictionaryIndex!))
    default:
        return JSONIndex()
    }
}