code: def _convert_string_to_hhmmss(self, string):
          
          # assume input string is 'hh:mm:ss'
          components = string.split(':')
          if len(components) != 3:
              raise InvalidArgument('time input string must be hh:mm:ss format')
          return {
              'hours': int(components[0]),
              'minutes': int(components[1]),
              'seconds': int(components[2])
          }
docs: stub