code: def seqfy(strs):
      ''' 序列化 字符串--->实际效果是，为字符串，添加行号，返回字符串
      Sampe usage:
          strs = ["", None, u"First-line\nSecond-line\nThird-line", u"没有换行符"]
          for s in strs:
              print "---"
              result = seqfy(s)
              print result
              print unseqfy(result)
      '''
      
      if not strs:
          return
      
      result = ""
      seq = 1
      ss = strs.split("\n")
      for i in ss:
          if i:
              result = "".join([result, str(seq), ".", i, "\n"])
              seq = seq + 1            
      return resulf seqfy(strs):
      ''' 序列化 字符串--->实际效果是，为字符串，添加行号，返回字符串
      Sampe usage:
          strs = ["", None, u"First-line\nSecond-line\nThird-line", u"没有换行符"]
          for s in strs:
              print "---"
              result = seqfy(s)
              print result
              print unseqfy(result)
      '''
      
      if not strs:
          return
      
      result = ""
      seq = 1
      ss = strs.split("\n")
      for i in ss:
          if i:
              result = "".join([result, str(seq), ".", i, "\n"])
              seq = seq + 1            
      return result
docs: 序列化 字符串--->实际效果是，为字符串，添加行号，返回字符串
      Sampe usage:
          strs = ["", None, u"First-line\nSecond-line\nThird-line", u"没有换行符"]
          for s in strs:
              print "---"
              result = seqfy(s)
              print result
              print unseqfy(result)