尝试将函数转发给变量，在JavaScript中可能会有

someFunc = someFuncAnotherTile

这样就可以保留参数。
在生 rust ，我如何才能做到这一点，例如在一个实现

#[OpenApi]
impl TestRoutesApi {
    // Old annoying way
    // #[oai(path = "/test-hello", method = "get")]
    // pub async fn test_hello(&self) -> PlainText<String> {
    //     PlainText(format!("hello"))
    // }

    // Passing function, but it doesn't work.
    #[oai(path = "/test-hello", method = "get")]
    pub async fn test_hello -> test_hello;