Sometimes I just want to test a package under the zope namespace (installed usually in /opt/Zope2.9/lib/python or /usr/local/Zope3.2/lib/python), like for example the zope.testbrowser the other day. The easiest way to achieve this, without messing around with PYTHONHOME environment variables, or appending paths to sys.path is to change directory to the lib/python folder and start the python interpretor there. Because python will look in the current folder for modules and packages, they will be available in the interpretor. Profit! :-)