#!/usr/bin/env python3
import cgi

print("Content-Type: text/plainn")

form = cgi.FieldStorage(keep_blank_values=1)
print(*form)

$ python3 -mhttp.server --cgi --bind localhost

$ python -mwebbrowser "http://localhost:8000/cgi-bin/script.py?6&20&21&22&23"

21 23 22 6 20