You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/tower/tower/src/hedge
    
    the code of the file until where you have to start completion: //! Pre-emptively retry requests which have been outstanding for longer
//! than a given latency percentile.

#![warn(missing_debug
    
    fn delay(&self, _req: &Request) -> Duration {
        let mut locked = self.histo.lock().unwrap();
        let millis = locked
            .read()
            .value_at_quantile(self.latency_percentile.into());
        Duration::from_millis(millis)
    }