If you are lucky (working with a mature codebase), tests are my number one go to when getting started. I need to know input/output of things. I work in ml space

If you are lucky (working with a mature codebase), tests are my number one go to when getting started. I need to know input/output of things. I work in ml space so ymmv. This allows me to make small changes and check my assumptions as I gain more confidence around the codebase