code: def folder_cls_from_folder_name(cls, folder_name, locale):
          
          for folder_cls in cls.WELLKNOWN_FOLDERS + NON_DELETEABLE_FOLDERS:
              if folder_name.lower() in folder_cls.localized_names(locale):
                  return folder_cls
          raise KeyError()
docs: Returns the folder class that matches a localized folder name.
  
          locale is a string, e.g. 'da_DK'