Merging a patch/diff generated by difflib?

[erikcw]

Hi,

I'm trying to create an undo/redo feature for a webapp I'm working on
(django based).  I'd like to have an undo/redo function.

My first thought was to use the difflib to generate a diff to serve as
the "backup", and then if someone wants to undo their operation, the
diff could just be merged/patched with the current text.

However, I've not be able to find a patch library.  Are there any
libraries that will handle merging the diff back into the text?

Thanks!