/**
  * @param string $arg
  *
  * @return string
  */
 protected function escapeArg($arg)
 {
     // Get a blank ArgvInput object so we can use the 'escapeToken' method.
     $argv = new ArgvInput();
     // If the string looks like an option=value pair, split them up.
     if ($arg[0] === '-' && strpos($arg, '=')) {
         list($option, $value) = explode('=', $arg, 2);
         return $option . '=' . $argv->escapeToken($value);
     }
     if (strpos($arg, '-') === 0) {
         return $arg;
     }
     return $argv->escapeToken($arg);
 }