how to diff one file in working dir against a Blob?

pygit2 version python3-pygit2-0.23.3-2.fc23.x86_64

I cannot figure out how I can get a diff for only one file.

How do I arrange to have pygit2 return the diff of a Blob against the working dir file?

I looked at calling diff_to_working on a new Index(), but that fails because the new Index() does not
self._repo filled in.

TreeBuilder() seems is unable to help as it requires putting tree objects into the repo to allow
for the folder structure, for example to diff Source/file.py. needs a tree for Source. I clearly
do not want to be writting files into the repo to do a diff.

Did I miss something in API?

Inizia esaminando le API diff_to_working e Index menzionate nell’issue, insieme al modo in cui pygit2 rappresenta un Blob e un file della directory di lavoro. Determina se un’API esistente supporta questo confronto senza creare oggetti albero del repository; il lavoro è completato quando è stato identificato o specificato un percorso supportato per un diff tra un singolo Blob e l’albero di lavoro.