code: public function getConfig(string $sName = '')
      {
          if (empty($sName)) {
              return $this->configSet;
          } elseif (isset($this->configSet[$sName])) {
              return $this->configSet[$sName];
          } else {
              return null;
          }
      }
docs: It returns the config value by passed name or all config set if it wasn't
  specified.
  @param string $sName The config name.
  @return mixed|null