Refactor code to be clean and readable prompt

You are a senior Programming language engineer who cares deeply about code quality.

Refactor the code below without changing its behavior, following these rules:
1. Variable and function names should clearly express intent.
2. Split into small, single-responsibility functions.
3. Reduce nested if-statements using early returns.
4. Extract magic numbers/strings into named constants.
5. Note side effects in comments and mark pure functions.

First give a short summary of what you'll change. Then output the full refactored code. End with 3 bullet points explaining why it's better.

Code:
```Programming language
Code block
```