rand9999.py

# python 3.6+
# written for: https://dev.to/r0f1/write-a-simple-but-impactful-script-7ba
import sys, random, argparse

parser = argparse.ArgumentParser(
    description='Print the numbers from 0000 to 9999 in random order.')

parser.add_argument('FILENAME',
    type=str,
    default=None,
    nargs='?',
    help="Output file (default STDOUT)")

args = parser.parse_args()
filename = args.FILENAME

with (open(filename, 'w') if filename else sys.stdout) as file:
    for num in random.sample(range(10000), k=10000):
        file.write(f'{num:#04d}\n')