看了swift handyjson的源码，有一段看不明白

func extensions(of value: Any) -> AnyExtensions {
    struct Extensions : AnyExtensions {}
    var extensions: AnyExtensions = Extensions()
    withUnsafePointer(to: &extensions) { pointer in
        UnsafeMutableRawPointer(mutating: pointer).assumingMemoryBound(to: Any.self).pointee = value
    }
    return extensions
}
这个函数是用来做什么的呢，这样不是会导致类型和内存的内容不一致吗，为什么可以这么写呢