From January 2021 to the beginning of 2023, I worked on a legacy code base at Fraunhofer IDMT in Oldenburg. My task was the maintenance and development of a DNN-based speech recognition engine that had become terra incognita when its original developer had left the company a year before I started. The code had all the hallmarks of severe technical debt, with layers of half-used abstractions, many unused branches of unknown utility, and the handwriting of several concurrent programmers at odds...