A script people run from a terminal takes flags. argparse builds that interface. In this editor there is no real argv, so you set sys.argv yourself.

Goal

Parse --city and --units, then print a kiosk line.

Fake argv, real parser

import argparse
import sys

sys.argv = ["kiosk", "--city", "Nairobi", "--units", "3"]

parser = argparse.ArgumentParser(description="Kiosk line")
parser.add_argument("--city", default="Nairobi")
parser.add_argument("--units", type=int, required=True)
args = parser.parse_args()
print(args.city, args.units)

Wire it to a helper

import argparse
import sys

def line_total(units, price, tax=0.16):
    return round(units * price * (1 + tax), 2)

def main(argv):
    parser = argparse.ArgumentParser()
    parser.add_argument("--city", default="Mombasa")
    parser.add_argument("--units", type=int, default=1)
    parser.add_argument("--price", type=float, default=10.5)
    args = parser.parse_args(argv)
    print(args.city, line_total(args.units, args.price))

if __name__ == "__main__":
    main(["--city", "Nakuru", "--units", "4"])

Passing argv into main makes the function testable without touching sys.argv.

Tip

On a laptop you would run python kiosk.py --city Nairobi --units 3. Here, pass a list to parse_args or set sys.argv.