sage

54535351 -

gh-38507: some code details in asymptotic just a few small enhancements in the modified file in particular, using the lazy power series ring at some point also avoid using `SR('a')` ### :memo: Checklist <!-- Put an `x` in all the boxes that apply. --> - [x] The title is concise and informative. - [x] The description explains in detail what this PR is about. URL: https://github.com/sagemath/sage/pull/38507 Reported by: Frédéric Chapoton Reviewer(s): Daniel Krenn, Matthias Köppe