> if your code doesn't work it doesn't work Code can definitely only sort of work: only works on the happy path, only works on the computer it was developed on

> if your code doesn't work it doesn't work Code can definitely only sort of work: only works on the happy path, only works on the computer it was developed on, only works for some versions of some dependencies, only works when single threaded, only works when the network is fast enough, only works for a single user at a time etc etc etc.