I thought it already was, because of this line in setup.py:

However, someone recently installed it from pip, and pip did not install the xlwt dependency. I suspect that perhaps this has been an error all along, but no one has yet tried to call one of the methods writing Excel files.

I tried finding documentation for the requires keyword for the function setuptools.setup, but I can't find any. I think it should be install_requires instead, which we are already using on this line:

Looking at the source code for setuptools.setup, its type signature is

def setup(**attrs):

So I think if you give it a keyword argument it doesn't expect, it simply ignores it, which is why this error was silent for so long.