The patch file gives the output of the execution of the code.

A basic example would be - run 'find -name '*.py' -execdir sed -i 's/foo/bar/g' +' on a repo, and commit the result.

For those not familiar with POSIX shell stuff, that will find and replace 'foo' with 'bar' across the repo.

The command is far more understandable at a glance than the patch (commit) and is far more likely to be reviewed properly.