async _send_file(live_file, callback) {
        // Wait for LiveFile to be ready before serving
        if (!live_file.is_ready) await live_file.ready();

        // Write appropriate extension type if one has not been written yet
        this.type(live_file.extension);

        // Send response with file buffer as body
        this.send(live_file.buffer);

        // Execute callback with cache pool, so user can expire as they wish.
        if (callback) setImmediate(() => callback(FilePool));
    }
@private
Sends file content with appropriate content-type header based on file extension from LiveFile.

@param {LiveFile} live_file
@param {function(Object):void} callback