code: def _check_building_options(string):
      
      opener, closer = '{', '}'
      _check_enclosing_characters(string, opener, closer)
      if opener in string:
          if string[-1] != closer:
              raise ValueError(OPTIONS_NOT_LAST)
          ret = True
      else:
          ret = False
      return ret
docs: Checks the building options to make sure that they are defined last,
      after the task name and the dependencies