Martin Fowler, author of “Refactoring” and signatory of the Agile Manifesto, created this analogy with the Strangler Fig. He was imagining a legacy application gradually being replaced by a new system. A hallmark of the approach is that for a while in the middle, both the old and the new system co-exist.
TODO: create a good exercise for this
Pose this question: Have you ever worked on code that was so bad it made you want to find a new job?