public function has($key, $type = self::CONFIG_ALL)
    {
        return null !== $this->get($key, $type);
    }
public function has($key, $type = self::CONFIG_ALL)
    {
        return null !== $this->get($key, $type);
    }
public function has ( $ key , $ type = self :: CONFIG_ALL ) { return null !== $ this -> get ( $ key , $ type ) ; }
Checks whether the config exists.

Note. A value with null is considered undefined.

@param string $key  Single level key like "adapters" or property-path
"[adapters][github]"
@param string $type Either Config::CONFIG_SYSTEM Config::CONFIG_LOCAL
or Config::CONFIG_ALL

@return bool
Checks whether the config exists .