code: def get_sn(unit):
      
      sn = 0
      match_re = re.findall(str(sentence_delimiters), unit)
      if match_re:
          string = ''.join(match_re)
          sn = len(string)
      return int(sn)
docs: 获取文本行的句子数量
  
      Keyword arguments:
      unit                    -- 文本行
      Return:
          sn                  -- 句数