- Always use tests to demonstrate the existence of a bug before fixing the bug.
  - If you suspect that a bug exists, use a test to demonstrate it first:
    - prefer unit tests testing a small amount of code to integration or e2e tests
- Option<...> or Result<...> are fine but should not be present in the majority of the code.
- Similarly, code managing  Box<...> or RC<...>, etc. for containers pointing to heap data should be split
  from logic