Review request [commit:6828275f7235c14c1220e65be943ef2f83978693: Fixed _resource_callback code to accept kwargs]
I rebased this code off of the master branch on 8/13/2019. Please let me know if this looks good. I haven't cleaned up commented-out code. I can do that now, or if you'd like to review first, I can do it if the code passes.