code: def get_folder_list(folder='.'):
      
      dir_list = get_content_list(folder)
      return [f for f in dir_list if not os.path.isfile(os.path.join(folder, f))]
docs: Get list of sub-folders contained in input folder
  
      :param folder: input folder to list sub-folders. Default is ``'.'``
      :type folder: str
      :return: list of sub-folders
      :rtype: list(str)