(Python) pip install using the testpypi repository

After fiddling sometime with Python pip command parameters, trying to let it use the https://testpypi.python.org repository instead of the default pypi repository. I found the comnand to use is:

pip install -i https://testpypi.python.org/simple/ <package name>

Note the simple part… Even the offical website documented it wrong. ¹