In Part I, we covered surface-level improvements—simple ways to improve the readability of your code one line at a time that can be applied without much risk or effort.

In this next part, we go deeper and discuss the “loops and logic” of your program: the control flow, logical expressions, and variables that make your code work. As always, our goal is to make these parts of your code easy to understand.

We do this by trying to minimize the “mental baggage” of your code. Every time you see a complicated loop, a giant expression, or a large number of variables, this adds to the mental baggage in your head. It requires you to think harder and remember more. This is exactly the opposite of “easy to understand.” When code has a lot of mental baggage, bugs are more likely to go unnoticed, the code becomes harder to change, and it’s just less fun to work with.