rewrite 4th column

parse_csv.py

import csv

def main():
    old_file = input('please give file name: ')
    new_file = old_file + '.updated'
    with open(old_file) as old, open(new_file, 'w') as new:
        writer = csv.writer(new)
        for row in csv.reader(old):
            if row[4] == 'MIS':
                row[3] = row[3].replace('.com', '.net')
            writer.writerow(row)
    print('wrote results to ' + new_file + ', replace ' + old_file + ' with it once you are sure everything is fine.')