Question: Interactive Execution. Start the Python interactive interpreter. You can invoke it by typing in its full pathname or just its name (python or python.exe) if you have installed its location in your search path. (You can al souse the Python interpreter compiled in Java jpython or jpython.exe] if you wish.) The startup screen should look like the ones depicted in this chapter. When you see the ">>>," that means the interpreter is ready to accept your Python commands. Try entering the command for the famous Hello World! program by typing print "Hello World!," then exit the interpreter. On Unix systems, Ctrl-D will send the EOF signal to terminate the Python interpreter, and on DOS systems, the key press is Ctrl-Z. Exiting from windows in graphical user environments like the Macintosh, Python Win or IDLE on Windows, or IDLE on Unix can be accomplished by simply closing their respective windows.