Python remove duplicates from CSV

import csv

reader=csv.reader(open('UserstoImport.csv', 'r'), delimiter=',')
writer=csv.writer(open('UserstoImport_withoutduplicates.csv', 'w'), delimiter=',')

entries = set()

for row in reader:
   key = (row[1], row[2]) # CSV rows by num

   if key not in entries:
      writer.writerow(row)
      entries.add(key)

awesome, thanks!