unknown404-practice/Centralized-repository-shipping_calculations — reverse-engineered prompt

Build me a simple Python shipping cost calculator for logistics rates. I want someone to be able to run it, enter basic shipment details, and get an estimated shipping cost with a clear explanation of how the total was calculated.

Keep it easy for a beginner to understand and maintain. Use readable code, simple prompts, input validation, and helpful messages if someone enters bad values. Since the README doesn’t explain the business rules, use sensible sample rate rules inside the code and make them easy to change later.

Please clean up or rewrite the existing script as needed, add comments where they help, and include a short README section that explains how to run it and shows an example. If it makes sense, add a couple of basic tests or sample checks so future changes don’t break the calculator.