import re
input = ['90-10-07457', '000480087800784', '001-713-0926', '12-710-8197', '1-345-1715', '9-23-4532', '000200007100272']
output = ['00090-00010-07457', '000480087800784', '00001-00713-00926', '00012-00710-08197', '00001-00345-01715', '00009-00023-04532', '000200007100272']

## I have tried this -

import re
new_list = []
for i in range (0, len(input)):
    splits = input[i].split('-')
    if len(splits) == 1:
        new_list.append(input[i])
    else:
        new_list.append("{}-{}-{}".format(splits[0].zfill(5), splits[1].zfill(5), splits[2].zfill(5)))

## problem is with second argument '0000\\1'. I know its wrong but unable to solve
print(new_list)  ## new_list is the expected output.
print(output)