public function pipe(ExecutableInterface $process, $_ = null)
    {
        foreach (func_get_args() as $index => $process) {
            if ($process instanceof ExecutableInterface) {
                $this->processes[] = $process;
            } else {
                $message = 'Argument ' . $index . ' passed to ' . __METHOD__ .
                    '() must implement interface ' .
                    'Net\Bazzline\Component\ProcessPipe\ExecutableInterface' .
                    ', instance of ' . get_class($process) . ' given';
                throw new InvalidArgumentException($message);
            }
        }

        return $this;
    }