Exclude/Include Symbols

[rowrowrowrow]

It would be useful to be able to exclude or include differences based on a type like their "symbol". This way we could ignore or focus on differences of a certain kind. I.e. in my case to do a "rightonly" diff and ignore deletions. This would confirm that "right" is a subset of "left".

[corytodd]

This feels like a job for post-processing. Maybe this could be done with a custom dumper. We currently have a json and yaml dumper, an instance of which can be passed in as the dumper kwarg in diff.

This might be a fairly flexible option. What do you think?