python单选按钮value_如何使用单选按钮为Python中的变量赋值？

我尝试使用python中的单选按钮为变量赋值，代码如下：def print_me():

global payment

global membership

if studentMemString == "PY_VAR0":

membership = "STUDENT"

payment = studentMem

elif adultMemString == "PY_VAR10":

membership = "ADULT"

payment = adultMem

elif childMemString == "PY_VAR0":

membership = "CHILD"

payment = childMem

else:

pass

print(membership)

print(payment)

root = tk.Tk()

studentMem = tk.StringVar()

studentMemString = str(studentMem)

adultMem = tk.StringVar()

adultMemString = str(adultMem)

childMem = tk.StringVar()

childMemString = str(childMem)

studentRadBtn = tk.Radiobutton(root, text="Student - £19.99",