public function app_path($path = null)
    {
        return empty($path) ? $this->base_path() . DIRECTORY_SEPARATOR . 'app' : $this->base_path() . 'app' . $path;
    }
public function app_path($path = null)
    {
        return empty($path) ? $this->base_path() . DIRECTORY_SEPARATOR . 'app' : $this->base_path() . 'app' . $path;
    }
public function app_path ( $ path = null ) { return empty ( $ path ) ? $ this -> base_path ( ) . DIRECTORY_SEPARATOR . 'app' : $ this -> base_path ( ) . 'app' . $ path ; }
To get application app directory path

@param null $path

@return string
To get application app directory path