设计一个名为Stock的类来表示一个公司的股票，包括以下内容： 1）股票代码、股票名称、前一天股票价格、当天股票价格4个私有属性； 2）构造方法，需初始化代码、名称、前一天价格和当天价格等属性； 3）返回股票名字的get方法; 4）返回股票代码的get方法; 5）获取和设置股票前一天价格的get和set方法; 6）获取和设置股票当前价格的get和set方法; 7）名为getChangePercent()方法，返回前日收市价至当前价格的变化百分比； 8). 包括文档字符串，其内容为:"Stock Information Class" 说明：各方法的名称及参数要求请参见测试程序。

以下是Stock类的代码实现：

class Stock:
    """
    Stock Information Class
    """
    def __init__(self, code, name, prev_price, cur_price):
        """Initialize the stock attributes"""
        self._code = code
        self._name = name
        self._prev_price = prev_price
        self._cur_price = cur_price
    
    def get_name(self):
        """Return the name of the stock"""
        return self._name
    
    def get_code(self):
        """Return the code of the stock"""
        return self._code
    
    def get_prev_price(self):
        """Return the previous price of the stock"""
        return self._prev_price
    
    def set_prev_price(self, prev_price):
        """Set the previous price of the stock"""
        self._prev_price = prev_price
    
    def get_cur_price(self):
        """Return the current price of the stock"""
        return self._cur_price
    
    def set_cur_price(self, cur_price):
        """Set the current price of the stock"""
        self._cur_price = cur_price
    
    def get_change_percent(self):
        """Return the percentage change between previous and current stock prices"""
        return (self._cur_price - self._prev_price) / self._prev_price * 100

测试程序的代码如下：

# Test the Stock class
stock = Stock("AAPL", "Apple Inc.", 120, 130)
print(f"Stock name: {stock.get_name()}")
print(f"Stock code: {stock.get_code()}")
print(f"Previous stock price: {stock.get_prev_price()}")
print(f"Current stock price: {stock.get_cur_price()}")
print(f"Percentage change: {stock.get_change_percent()}%")

输出结果如下：

Stock name: Apple Inc.
Stock code: AAPL
Previous stock price: 120
Current stock price: 130
Percentage change: 8.333333333333334%