How to use Unity WWW class to yield return www object before upload finishes?

Basically my server will return a response early to let me know a large upload has begun and finish the upload in background. Right now WWW is waiting until the upload finishes to return the web response. Please help

using (WWW www = new WWW(url, stream.ToArray(), head)) {
      yield return www;
      // upload not finished yet, but Nodejs response sent on upload started 
      StartCoroutine(SendUploadProgressRequest());
    }

@Chris333 @SneeKeeFahk

You can use WWW class without ‘using block’. Here’s an example:

public class YourClassName: MonoBehaviour
{
    // stuff

    WWW w;

    public void StartDownload(string url)
    {
        w = new WWW(url);
    }

    public bool IsDownloadComplete()
    {
        return w.isDone;
    }

    // Stuff
}