public function __construct($browser = null, $version = null, $platform = null)
{
if (isset($browser)) {
$this->setCapability(CapabilityType::BROWSER_NAME, $browser);
}
if (isset($version)) {
$this->setCapability(CapabilityType::VERSION, $version);
}
if (isset($platform)) {
$this->setCapability(CapabilityType::PLATFORM, $platform);
}
}