It usually starts with one boolean. Then people avoid touching it when expending a bit, so they just add another boolean for the corner case they're dealing wi

It usually starts with one boolean. Then people avoid touching it when expending a bit, so they just add another boolean for the corner case they're dealing with (potentially as an optional last param). And so on, until someone refactors the whole function bearing the burden to retouch all its legacy that accumulated up to that point.