code: def make_spondaic(self, scansion: str) -> str:
          
          mark_list = string_utils.mark_list(scansion)
          vals = list(scansion.replace(" ", ""))
          new_vals = self.SPONDAIC_PENTAMETER[:-1] + vals[-1]
          corrected = "".join(new_vals)
          new_line = list(" " * len(scansion))
          for idx, car in enumerate(corrected):
              new_line[mark_list[idx]] = car
          return "".join(new_line)
docs: If a pentameter line has 12 syllables, then it must start with double spondees.
  
          :param scansion: a string of scansion patterns
          :return: a scansion pattern string starting with two spondees
  
          >>> print(PentameterScanner().make_spondaic("U  U  U  U  U  U  U  U  U  U  U  U"))
          -  -  -  -  -  -  U  U  -  U  U  U