codesmell: breaks when import pycoq is omitted even tho pycoq is not invoked.

[quinn-dougherty]

when I comment out import pycoq, I get

dune exec -- python3 _build/default/examples/add_commutative.py
Traceback (most recent call last):
  File "_build/default/examples/add_commutative.py", line 2, in <module>
    import coq
ModuleNotFoundError: No module named 'coq'
make: *** [Makefile:14: examples] Error 1

even tho pycoq is not invoked at all in add_commutative.py. This means we are guaranteed to raise the lint message "no unused imports" (unless we ignore that rule, which we do in my upcoming PR).

[ejgallego]

I think import pycoq is needed so the .so file with the coq module is loaded?