> For the complete documentation index, see [llms.txt](https://drlilianblot.gitbook.io/introduction-to-programming-with-python/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://drlilianblot.gitbook.io/introduction-to-programming-with-python/a-deeper-look-at-functions-in-python/glossary.md).

# Glossary

**temporary variable:** A variable used to store an intermediate value in a complex calculation. 

**dead code:** Part of a program that can never be executed, often because it appears after a `return` statement.

**`None`:** A special value returned by functions that have no return statement or a return statement without an argument. 

**incremental development:** A program development plan intended to avoid debugging by adding and testing only a small amount of code at a time. 

**scaffolding:** Code that is used during program development but is not part of the final version. 

**guardian:** A programming pattern that uses a conditional statement to check for and handle circumstances that might cause an error.