I know that others have run into the same exception (NameError: name 'cbclib' is not defined), but my setup is different. My goal is to run the solver in a docker container on 32 bit Raspberry Pi (arm ...

This will install the function _() in Python’s builtins namespace, When registering a custom built-in in Pythons namespace then mypy does not recognize that as such and reports it as an unknown.