Leader instead string

[Ed Summers]

This is just a heads up that Jeremy Nelson has put up a pull request [1] to have Recorder.leader always return a Leader object instead of a str.

An instance of Leader [2] behaves like a string, but unlike a str it is mutable, and has a properties you can get and set without needing to remember their offset position.

I don’t think this change should cause any problems, but I wanted to get your feedback to let you know it’s being considered for the next release.

//Ed

[1] https://gitlab.com/pymarc/pymarc/-/merge_requests/209
[2] https://pymarc.readthedocs.io/en/latest/#module-pymarc.leader