use tokio::io::AsyncWriteExt;

                    use tokio::io::AsyncWriteExt;

        f.flush().await?;

        let mut size = res
            .headers()
            .get(reqwest::header::CONTENT_LENGTH)
            .and_then(|x| x.to_str().ok())
            .unwrap_or("0")
            .parse::<usize>()
            .ok();

                Ok(Some(chunk)) => send.send(Some(chunk)).await?,
                Ok(None) => done = true,

                Ok(Some(chunk)) => {
                    if let Some(ref mut s) = size {
                        *s -= chunk.len();
                    }
                    send.send(Some(chunk)).await?;
                }
                Ok(None) => match size {
                    Some(0) | None => done = true,
                    _ => break,
                },