I understand that I cannot conveniently directly modify this Pull Request because this would imply updating the master branch of lmfit. So if you can do the 3 changes, that would be great! Otherwise I can do a PR on lmfit/uncertainties. :)

@lebigot Python 2 had extended support but reached end-of-life 4 years ago. I hope you'll understand that I think it is not worth supporting.

I may not remember subtleties of Python2, but I don't quite understand why those u'..' strings would need changing to use double backslash while others close by that were not u'...' in the current master would be OK to leave as r'...'. So, I'm not 100% sure what would be the best changes to make to allow support for Python 2. You could consider merging this and then fixing it as you like.

FWIW, you were invited to join the lmfit organization. These invitations expire after 7 days, but I just resent it. I hope you'll have time to accept that invitation.

Please consider the offer in #180. We're willing to support this great library and try to move it forward. If you take a few steps to help us be able to push releases to PyPI and offer advice when you can, that would be tremendously helpful and very much appreciated. Otherwise, we could change the name of the forked project.

Cheers!