This is a way for arduino and python to exchange only some variables while still running their own programs. The communication on arduino is done with simple Serial.read and Serial.write, while on python two different programs are running at the same time. It is done by threading library.
Py2ArdComs.py takes care of communicating with arduino, while PythonMain.py runs at normal speeds and gets Serial information thru the first one.
Both arduino and python send only long intigers. Chars and strings are going to cause error.