export models defined in code

[FynnBe]

going from model class/instance in code to the spec is indeed not trivial.

we could try to write the file automatically with inspect.getsource
we'd have to somehow make sure to also include the correct imports though... (maybe that could be left to the user who'll have to provide the env as well.. of course using conda env export --from-history could be a start to make it more convenient for some users)....

Originally posted by @FynnBe in #417 (comment)