Declarative programming is an enabler of abstraction. Imperative programming is an inhibitor of abstraction. Declarative programming allows you to say “I want this and I don’t care how I get it” while imperative programming requires you to define each and every step.

detach, as an api, should be declarative (ensure the node is detached) instead of imperative (detach the node), allowing it to be called multiple times by performing a noop if the node is already detached. This way, it won't matter if the node is removed from the DOM from outside of svelte.