1. Please tweak the docstring for TreeTransformBase so it doesn't claim to be a base class for itself. :-)
2. You're changing the constructor interface for TreeTransformBase which is technically public (but practically private). I think we should therefore mention this refactoring in the Internals sections of NEWS.
All looks good to me. Two minor things:
1. Please tweak the docstring for TreeTransformBase so it doesn't claim to be a base class for itself. :-)
2. You're changing the constructor interface for TreeTransformBase which is technically public (but practically private). I think we should therefore mention this refactoring in the Internals sections of NEWS.