5 - Subroutines and Modules

Summary

This chapter explains functions and modules. Functions perform some operation. They can operate directly on data or indirectly via other functions. All the niceties of different kinds of functions are explained. In addition, the topic treats the concept of modules, bits of code that are available to you or other programmers. The chapter shows how you can use existing modules in your own code and how you can write your own modules for others. Finally, the chapter goes into the proper way to document your functions and modules.