Function cancel_handler 

pub async fn cancel_handler<Repo: Repository + Send + Sync + 'static, Search: SearchEngine + Send + Sync + 'static, Terminology: FHIRTerminology + Send + Sync + 'static>(
    __arg0: Extension<Arc<User>>,
    __arg1: Path<JobPath>,
    __arg2: State<Arc<ServerState<Repo, Search, Terminology>>>,
) -> Result<Response, OperationOutcomeError>

DELETE of the status URL: cancels the job, or, once it has finished, gives up its result. 202 Accepted either way; 404 if there is no such job or it was already cancelled.