docs: def perform_import(val):
      """
      If the given setting is a string import notation,
      then perform the necessary import or imports.
      """
      if val is None:
          return None
      elif isinstance(val, str):
          return import_from_string(val)
      elif isinstance(val, (list, tuple)):
          return [import_from_string(item) for item in val]
      return val