Function http_status_for 

pub const fn http_status_for(status: ReturnStatus, method: RestMethod) -> u16

Spec §8.3.2 + Tab in §8.3 — HTTP-Status-Code-Mapping.

Ok haengt vom HTTP-Method ab:

• POST (create) → 201 Created.
• DELETE → 204 No Content.
• GET → 200 OK.
• PUT (update) → 204 No Content.