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/pingora/pingora-core/src/modules/http
    
    the code of the file until where you have to start completion: // Copyright 2024 Cloudflare, Inc.
//
// Licensed under the
    
    pub fn add_module(&mut self, builder: ModuleBuilder) {
        if self.module_index.get().is_some() {
            // We use a shared module_index the index would be out of sync if we
            // add more modules.
            panic!("cannot add module after ctx is already built")
        }
        self.modules.push(builder);
        // not the most efficient way but should be fine
        // largest order first
        self.modules.sort_by_key(|m| -m.order());
    }