def kevent!(*flags)
      if Native.kevent(@queue.fd, native(flags).pointer, 1, nil, 0, nil) < 0
        KQueue.handle_error
      end
    end
def kevent!(*flags)
      if Native.kevent(@queue.fd, native(flags).pointer, 1, nil, 0, nil) < 0
        KQueue.handle_error
      end
    end
Runs the `kevent` C call with this Watcher's kevent struct as input.
 This effectively means telling kqueue to perform some action
 with this Watcher as an argument.

 @param flags [Array<Symbol>] Flags specifying the action to perform
   as well as any additional flags.
 @return [void]
 @raise [SystemCallError] If something goes wrong when performing the C call.