he program starts by importing the library modules it needs. It then creates an instance
of the classRaspiRobot and assigns it to the variablerr. The main loop first checks
for aQUIT event, and if it find one it exists the program. The rest of the loop is concerned
with checking all of the keys and issuing the appropriate commands if a key is pressed.
For example, if the UP ARROW key (K_UP) is pressed, the RaspiRobot is sent the command
forward, which sets the motors to both go forward as well as sets both LEDs on.