code: public function cachedTranslation($namespace, $group, $transKey, $locale)
      {
          $group = self::fixGroup($group);
          $group = $namespace && $namespace !== '*' ? $namespace . '::' . $group : $group;
  
          $cacheKey = $this->cacheKey($transKey, $locale);
          $value = $group && array_key_exists($group, $this->cache()) && array_key_exists($cacheKey, $this->cache[$group]) ? $this->cache[$group][$cacheKey] : null;
          return $value;
      }
docs: @param $namespace
  @param $group
  @param $transKey
  @param $locale
  
  @return string|null translation value