Calculate factorials over a range with Python

#!/usr/bin/env python3
import sys
import functools
start = int(sys.argv[1])
end = int(sys.argv[2])
for n in range(start, end + 1):
    factorial = 1 if n == 0 else functools.reduce(
        lambda x, y: x * y, range(1, n + 1)
    )
    print(f"{n}! = {factorial}")