to the interpretera program source file is python module we will tend to use the more general terma program file is module note the term from the menu when running the program distinguish program code from shell textit is easy to confuse the shell and the edit windows make sure you keep them straight the hello py program is just the line print('hello world!'that you typed into the edit window and saved when you ran the program in idleyou saw results in the shell first came the restart noticethe one-line output from the program saying helloand further shell prompt===============================restart =======hello worldyou could also have typed this single printing line directly in the shell in response to shell prompt when you see you could enter the print function and get the exchange between you and the shellprint('hello world'hello worldwarningthe three lines above are not program you could save in file and run this is just an exchange in the shellwith its promptsindividual line to executeand the response againjust the single linewith no print('hello world!'entered into the edit window forms program you can save and run the prompts have no place in python program file we will shortly get to more interesting many-statement programswhere it is much more convenient to use the edit window than the shellthe general assumption in this tutorial will be that programs are run in idle and the idle shell is the shell referred to it will be explicitly stated when you should run program directly from the operating system in general it is also fine to run our programs from cmd console (windowsor terminal (macor from different development environment warningrunning the text based example programs in windowslike birthday pyby selecting them to run from file folderwill not work wellthe program ends and the window automatically closes before you can see the final output on mac you get to explicitly close the verbose terminal window created when you run python program from the finder program documentation string the hello program above is self evidentand shows how short and direct program can be (unlike other languages such as javastillright awayget used to documenting program python has special featureif the beginning of program is just quoted stringthat string is taken to be the program' documentation string open the example file hello py in the edit window''' very simple programshowing how short python program can be beginning with python