Every function or piece of code should have one entry point (input) and one exit point (output). Edsger W. Dijkstra

About the implementation

• Do one thing. Be small!
• One level of abstraction per function.
• One level of indentation per function.
• Be pure: the return value is only determined by its input values, without observable side effects.

About readability

• Use Intention-Revealing Names: Choosing names that reveal intent can make it much easier to understand and change code.
• Avoid Disinformation: Avoid leaving false clues that obscure the meaning of code.
• Make Meaninful Dinstictions: It helps you group functions in different layers, from high to low level.
• Use Pronounceable names: If you are programming in a language, make possible read it.

About the interface

• One or two arguments is nice, never more than three.
• Never flags arguments.

About the workflow

• Sort function from high level to low level.
• Warning with wreck train (don’t talk to strangers).