Unit Price: 10.99
Quantity: 3
Shipping Cost: 5
Tax Rate: 0.03
创建一个函数来计算书籍订单的总成本，给定单位价格、数量、运费和税率。
def calculateCost(unitPrice, quantity, shippingCost, taxRate): 
    totalPrice = (unitPrice * quantity) + shippingCost
    totalTax = totalPrice * taxRate
    totalCost = totalPrice + totalTax
    return totalCost