type_annotation.py

def open_account(
    balances: dict[str, int],
    name: str,
    amount: int,
) -> None:
    balances[name] = amount

def sum_balances(accounts: dict[str, int]) -> int:
    total = 0
    for name, pence in accounts.items():
        print(f"{name} had balance {pence}")
        total += pence
    return total

def format_pence_as_string(total_pence: int) -> str:
    if total_pence < 100:
        return f"{total_pence}p"

    pounds = int(total_pence / 100)
    pence = total_pence % 100

    return f"£{pounds}.{pence:02d}"

balances = {
    "Sima": 700,
    "Linn": 545,
    "Georg": 831,
}

open_account(balances, "Tobi", 913)
open_account(balances, "Olya", 713)

total_pence = sum_balances(balances)
total_string = format_pence_as_string(total_pence)

print(f"The bank accounts total {total_string}")