How do you approach improving and rethinking existing code?

The approach to improving and rethinking existing code usually involves several steps:

1. Analyzing the current state — understanding what the code does, identifying issues (such as duplication, complexity, poor readability).
2. Test coverage — if tests are not present, writing tests to ensure that changes do not break functionality.
3. Refactoring — improving the code structure without changing its behavior: extracting functions, simplifying logic, removing duplication.
4. Optimization — if necessary, enhancing performance or using more suitable algorithms.
5. Documentation — adding comments and documentation for better understanding.

For example, if there are many repeating blocks in the code, they can be extracted into a separate function and used everywhere, improving readability and maintainability.