请编写小微企业《销售管理》轻应用模块程序编码

小微企业《销售管理》轻应用模块程序编码可以参考以下示例：

class SalesManagementApp:
    def __init__(self):
        self.products = []
        self.customers = []
        self.orders = []

    def add_product(self, product):
        self.products.append(product)

    def add_customer(self, customer):
        self.customers.append(customer)

    def place_order(self, customer_id, product_id, quantity):
        customer = self.find_customer(customer_id)
        product = self.find_product(product_id)

        if customer and product:
            order = Order(customer, product, quantity)
            self.orders.append(order)
        else:
            print("Invalid customer or product!")

    def find_customer(self, customer_id):
        for customer in self.customers:
            if customer.id == customer_id:
                return customer

        return None

    def find_product(self, product_id):
        for product in self.products:
            if product.id == product_id:
                return product

        return None

class Product:
    def __init__(self, id, name, price):
        self.id = id
        self.name = name
        self.price = price

class Customer:
    def __init__(self, id, name, email):
        self.id = id
        self.name = name
        self.email = email

class Order:
    def __init__(self, customer, product, quantity):
        self.customer = customer
        self.product = product
        self.quantity = quantity

# 示例用法
app = SalesManagementApp()

# 添加产品
product1 = Product(1, "Product 1", 10.99)
product2 = Product(2, "Product 2", 15.99)
app.add_product(product1)
app.add_product(product2)

# 添加客户
customer1 = Customer(1, "Customer 1", "customer1@example.com")
customer2 = Customer(2, "Customer 2", "customer2@example.com")
app.add_customer(customer1)
app.add_customer(customer2)

# 下订单
app.place_order(1, 1, 2)
app.place_order(2, 2, 1)

上述代码示例中，定义了一个SalesManagementApp类作为销售管理应用模块的主类。该类包含了添加产品、添加客户和下订单的方法。产品、客户和订单分别定义为Product、Customer和Order类。

通过调用add_product和add_customer方法可以添加产品和客户到应用中。place_order方法用于下订单，需要传入客户ID、产品ID和数量。订单信息会被添加到应用的orders列表中。

示例中最后的用法部分展示了如何使用该应用模块的方法来进行销售管理操作