39     private $process;  variable in Facebook\\WebDriver\\Remote\\Service\\DriverService
68         if ($this->process !== null) {
72         $this->process = $this->createProcess();
73         $this->process->start();
75         $this->checkWasStarted($this->process);
88         if ($this->process === null) {
92         $this->process->stop();
93         $this->process = null;
106         if ($this->process === null) {
110         return $this->process->isRunning();
146      * @param Process $process
148     protected function checkWasStarted($process)  argument
152         if (!$process->isRunning()) {
156                     $process->getCommandLine(),
157                     $process->getErrorOutput()