code: protected function getThemeObject()
      {
          $themeObject = $this->getServiceLocator()
              ->get('yimaTheme.ThemeObject');
          if (! $themeObject instanceof ThemeDefaultInterface) {
              throw new \Exception(
                  sprintf(
                      'yimaTheme.ThemeObject must instanceof "\yimaTheme\Theme\ThemDefaultInterface" but "%s" given.',
                      get_class($themeObject)
                  )
              );
          }
  
          return $themeObject;
      }
docs: Get ThemeObject
  : it must be unique new instance object theme -
  on each get request
  
  @return Theme
  @throws \Exception