The Pyhton code has many HTTP commands available to modify program and stations via GET HTTP requests.
For more information on these commands please visit the documentation: http://rayshobby.net/wordpress/wp-content/uploads/2011/10/Firmware1.8HTTPGETcommands.pdf
Please note the above document is technically for the OpenSprinkler Arduino firmware however the Pi is based on the firmware and shares the same commands with a few exceptions.