Where can I learn what "being an opinionated framework, Amplify doesn't support batching" means?

I was following along until "Lastly, in the handleCSVSubmit function, replace the Papa.parse function with the following:" I can't find any string "Papa.parse" in my edited project nor in github.com/Focus-Otter/batch-upload.git Is there a completed version branch of batch-upload that can be added?