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: routes.rs
    path of file: ./repos/binserve/src/core
    
    the code of the file until where you have to start completion: use dashmap::DashMap;
use once_cell::sync::Lazy;

/// routes are usually small in size, store them in the
    
    pub fn add_error_pages() -> anyhow::Result<()> {
        let not_found_page = generate_not_found()?;

        let route_handle = RouteHandle {
            r#type: Type::Bytes,
            response: not_found_page,
        };

        ROUTEMAP.insert("{{404}}".into(), route_handle);

        Ok(())
    }