Software engineering starts with small pieces. A function should do one job, take named inputs, and return a value. print belongs at the edge — in main(), not inside every helper.

Goal

Split a kiosk total into helpers that return values, then print once.

Return, then print

TAX = 0.16

def line_total(units, price):
    return round(units * price * (1 + TAX), 2)

def format_kes(amount):
    return f"KES {amount:.2f}"

def main():
    total = line_total(3, 10.5)
    print("Nairobi")
    print(format_kes(total))

if __name__ == "__main__":
    main()

line_total does not print. Tests can call it without scraping the console.

Names that say what happened

def city_label(city):
    return str(city or "").strip().title()

print(city_label("  mombasa "))
print(city_label("kisumu"))

city_label is better than fn or process. Use snake_case for functions and variables.

Too much in one place

def report(units, price, city):
    tax = 0.16
    total = round(units * price * (1 + tax), 2)
    label = str(city).strip().title()
    print(label)
    print(total)
    return total

print("avoid this shape — helpers mixed with print")
report(2, 10.5, "nairobi")

That function computes, formats, and prints. Split it.

Pitfall

A function that only prints is hard to test. Return the value; print in main().