def loan(principle, annual_percentage_rate, payments_per_year, years):
    '''This function calculates monthly payment for a loan'''
    monthly_interest = annual_percentage_rate / payments_per_year / 100.0
    total_num_payments = yeras * payments_per_year
    val = (1 + monthly_interest) ** total_num_payments

    return round((principle * monthly_interest * val / (val - 1)), 2)

loan1 = loan(
    years = 5.0,
    principle = 13000.0,
    payments_per_year = 12.0,
    annual_percentage_rate = 4.0
)

print(loan1)