code: public function getAs(string $key, string $configClass, array $default = []) : Config
      {
          $data = $this->get($key, $default);
  
          if (! is_a($configClass, Config::class, true)) {
  
              $configInterface = Config::class;
  
              throw new \InvalidArgumentException("The given config-class '$configClass' does not implements $configInterface, but is has to.");
          }
  
          return new $configClass($data);
      }
docs: @inheritdoc
  
  @param string $key
  @param string $configClass
  @param array  $default
  
  @return Config