http_response.rs

fn request_start(self, head: Head, resp: &mut Response, scope: &mut Scope<C>)
    -> Option<Self>
{
    res.status(hyper::status::StatusCode::Ok);
    res.add_header(TransferEncoding(vec![Encoding::Chunked]).unwrap();
    res.done_headers().unwrap();
    self
}
fn request_chunk(self,  chunk: &[u8], resp: &mut Response, scope: &mut Scope<C>)
    -> Option<Self>
{
    res.write_body(
        format!("Received chunk of {} bytes\n", chunk.len()));
    self
}
fn request_end(self, _response: &mut Response, _scope: &mut Scope<C>)
    -> Option<Self>
{
    res.done();
    None
}

should resp: &mut Response be res: &mut Response?