“Writing code” is about making code that runs well. “Software engineering” is about making code that fails well. It’s about making code that is legible – whose functions can be understood by third parties who might be asked to maintain it, or might be asked to adapt the processes downstream, upstream or adjacent to the system to keep the system from breaking. It’s about making code that can be adapted, for example, when the underlying computer architecture it runs on is retired and has to be replaced, either with a new kind of computer, or with an emulated version of the old computer: