private function _recursivelyGetFromTheme(tubepress_api_theme_ThemeInterface $theme, $getter)
 {
     $toReturn = $theme->{$getter}($this->_environment->getBaseUrl(), $this->_environment->getUserContentUrl());
     $parentThemeName = $theme->getParentThemeName();
     if (!$parentThemeName) {
         return $toReturn;
     }
     $theme = $this->_themeRegistry->getInstanceByName($parentThemeName);
     if (!$theme) {
         return $toReturn;
     }
     $fromParent = $this->_recursivelyGetFromTheme($theme, $getter);
     if (is_array($fromParent)) {
         $toReturn = array_merge($fromParent, $toReturn);
     } else {
         $toReturn = $fromParent . $toReturn;
     }
     return $toReturn;
 }