$ pipenv install black Installing black… Collecting black Downloading https://files.pythonhosted.org/packages/db/c8/c587383e6b57a07b9937ac29ff93f845aa3d344aa9242f0eba13163eaa2b/black-18.4a4-py36-no...

Warning: Your dependencies could not be resolved. You likely have a mismatch in your sub-dependencies. · Issue #209 · psf/black