Resolved once the context has started. */ public function start(): Promise; /** * Immediately kills the context. */ public function kill(); /** * @return \Amp\Promise Resolves with the returned from the context. * * @throws \Amp\Parallel\Context\ContextException If the context dies unexpectedly. * @throws \Amp\Parallel\Sync\PanicError If the context throws an uncaught exception. */ public function join(): Promise; }