Function upload 

pub async fn upload<T, S>(
    transport: &mut T,
    src: &mut S,
    options: UploadOptions,
) -> Result<UploadStats, UploadError>
where
    T: AsyncRead + AsyncWrite + Unpin,
    S: AsyncRead + Unpin,

Available on crate feature tokio only.

Async equivalent of adapters::blocking::upload.