I'm opening this issue to propose the following enhancement
and a PR on GitHub.

Concerning: https://github.com/python/cpython/blob/main/Lib/string.py

The idea:
Format strings, that are comprised of field values with newlines (Multiline)
as Multiline strings in a quasi tabbed format.

--> In particular useful for logging of information, that occupies multiple lines.

For example: '{levelname}:{name}:{message}:{api}', 
             where the message and the api field is a string with multiple lines (contains newlines)

The result:   2021-07-23 09:50:28,981 module_name WARNING     Quota exceeded         Google-Cloud-API
                                                              Backing off for 5s     version: v1
                                                              after trying 2x

Can you provide a specification of what this class does? You’ve given an example, but not a description of the behavior.

Thank you.

In the process of providing that description I also just realized – after also seeing the build fail – that I'm making use of a library which is not part of the core (llist) for a doubly linked list.

That dependency is most probably a deal breaker and would require refactoring.

I suggest you close this issue and if you have an improved code, propose it on python-ideas list for discussion.

Thank you for your kind guidance :)