求两个文件交集

#!/usr/bin/env python
rd3 = open("data_17_17_2.csv")
base = open("data_17_17_3.csv")
wr3 = open("delNoBuyed3DayAndStoreAndInCar4.5.2.csv","w+")
bsData = base.readlines()
i = 1
for key in rd3:
  if key in bsData:
    wr3.write(key)
  if i == 1:
    print key
  i = (i + 1)%100

rd3.close()
base.close()
wr3.close()