code: def ReleaseFileSystem(self, file_system):
      
      identifier, cache_value = self._file_system_cache.GetCacheValueByObject(
          file_system)
  
      if not identifier:
        raise RuntimeError('Object not cached.')
  
      if not cache_value:
        raise RuntimeError('Invalid cache value.')
  
      self._file_system_cache.ReleaseObject(identifier)
  
      result = cache_value.IsDereferenced()
      if result:
        self._file_system_cache.RemoveObject(identifier)
  
      return result
docs: Releases a cached file system object.
  
      Args:
        file_system (FileSystem): file system object.
  
      Returns:
        bool: True if the file system object can be closed.
  
      Raises:
        PathSpecError: if the path specification is incorrect.
        RuntimeError: if the file system object is not cached or an inconsistency
            is detected in the cache.