Here is the solution when you try to install a python package using
python setup.py install or
pip install . and you get the error
ImportError: No module named Cython.
Try to upgrade or install cython in your virtualenv:
pip install --upgrade cython
You can also try to use pip module with python command, make sure you have activated your virtualenv:
python -m pip install --upgrade cython
Some environments could use
python3 command instead of just
python3 setup.py install
Leave a comment if the previous solution didn't work.