多个依赖小部件和函数

Question

我正在寻找一种方法来集成下面问题中作为示例提供的代码，在这里我可以添加多个可以一次动态更新的函数：

Multiple dependent widgets (dropdown menu) on Jupyter notebook

以修订后的示例为例，我想在另一个函数中定义total，当动态更新时，可以使用if __name__ == '__main__':。我可以通过向print_city函数添加代码来添加许多计算和新的小部件，但我想学习更好的方法，如果代码中有@interaction，我无法理解这是如何工作的

from ipywidgets import interact, Dropdown

geo = {'USA':['CHI','NYC'],'Russia':['MOW','LED']}
priceW = Dropdown(options = [105, 100, 80])
rateW = FloatText(200)

countryW = Dropdown(options = geo.keys())
cityW = Dropdown(options = geo[countryW.value])
districtW = Dropdown()

@interact(country=countryW, city=cityW, price=priceW, rate=rateW)
def print_city(country, city, price, rate):
    cityW.options = geo[country]
    priceW = price
    rateW = rate
    total = rate*price
    print('Total: ', total)

我正在寻找这样的东西，如果有意义的话：

from ipywidgets import interact, Dropdown

geo = {'USA':['CHI','NYC'],'Russia':['MOW','LED']}
priceW = Dropdown(options = [105, 100, 80])
rateW = FloatText(200)

def main():
    .....
    


countryW = Dropdown(options = geo.keys())
cityW = Dropdown(options = geo[countryW.value])
districtW = Dropdown()

@interact(country=countryW, city=cityW, price=priceW, rate=rateW)
def print_city(country, city, price, rate):
    cityW.options = geo[country]
    priceW = price
    rateW = rate
    
def totale():
    total = rate*price
    print('Total: ', total)
    

if __name__ == '__main__':
    main()