[rectangletangle]

It is an interesting approach, though I feel like this could introduce some nasty unintended consequences given how dynamic and introspective Python can be (admittedly I haven't studied this particular implementation).

I always treated this a bit like single underscore private functions/methods, i.e., follow a convention that produces code that's easy to reason about, even if it's not strictly enforced by the language/compiler. So in practice this equates to separating out modules that mutate global state, and placing the majority of logic in "strict" modules that only declare a bunch of "pure" classes/routines. So the "non strict" code is really just a thin layer of wiring gluing everything together. For instance my Celery task files tend to be very thin.

[ledauphin]

well, we also heavily use static typing, so you end up with something like

my_db_conn: Lazy[DbConn] = Lazy(lambda: make_db_conn(...))

and MyPy will tell you if you're doing something silly when you try to use it.

EDIT: After typing up this response and submitting I realize you were talking about their strict approach rather than ours. whoops :)