python将文本分每两行一组并保存到文件

# -*- coding: utf-8 -*-
'''
python读取文件，每两行为一组
'''
def fenhang(infile,outfile):

 infopen = open(infile,'r',encoding='utf-8')
 outopen = open(outfile,'w',encoding='utf-8')
 lines = infopen.readlines()
 i = 1
 for line in lines:
  if i % 2 == 0:
   outopen.write(line+'\n')
  else:
   outopen.write(line)
  i += 1
 infopen.close()
 outopen.close()
fenhang("jb51.txt","o.txt")