python - Why does inspect say that my module is built-in?

Question

mod = importlib.import_module('mortgagecomparison')
inspect.getsourcefile(mod)

Yields:

TypeError: <module 'mortgagecomparison' (namespace)> is a built-in module

But the module is not built-in, it's made by me, then installed a pip install -e ..

Answer 1

In the message:

module 'mortgagecomparison' (namespace)

indicates that this is not an imported module or package, just a directory name, presumably without an __init__.py