Interop\Async\Loop::cancel PHP Method

    public static function cancel($watcherId)
    {
        $driver = self::$driver ?: self::get();
        $driver->cancel($watcherId);
    }

 /**
  * {@inheritdoc}
  */
 public function cancel(\Throwable $e) : array
 {
     if ($this->state === self::PENDING) {
         Loop::cancel($this->watcher);
         $this->fail($e);
     }
     return [];
 }