$ PYTHONUSERBASE=/path/to/install/to pip install --user package
https://stackoverflow.com/questions/2915471/install-a-python-package-into-a-different-directory-using-pip
$ PYTHONUSERBASE=/path/to/install/to pip install --user package
https://stackoverflow.com/questions/2915471/install-a-python-package-into-a-different-directory-using-pip