Palindromic ISO dates between two years with #Python

#!/usr/bin/python3

import sys
from datetime import datetime
from itertools import chain

def palinDay(y):
s = str(y)
r = s[::-1]
iso = '-'.join([s, r[0:2], r[2:]])
try:
datetime.strptime(iso, '%Y-%m-%d')
return [iso]
except ValueError:
return []

palinDates = list(chain.from_iterable(
map(palinDay, range(int(sys.argv[1]),int(sys.argv[2])))
))
for x in [
"\n".join(palinDates),
]:
print(x)