Throughout this book, you’ve imported modules like
pygame into your programs to add functions for drawing, generating a random number, and animating graphics without having to code them from scratch. But did you know that you can also write your own modules and import them into your programs? Python makes it easy to build modules so you can save useful code and use it in many programs.
To create a reusable module, we write the module in IDLE’s file editor window just like other program files we’ve built, and we save it as a new .py file with the name of the module as the filename (for example, colorspiral.py might be the filename for a module that draws color spirals). We define functions ...