python 里 提示get（）方法 缺少了一个参数， 可是get（）方法是系统自带的啊，不需要参数啊，求解啊，大神

from tkinter import *
root = Tk()
frame = Frame(root)
frame.pack(padx = 10, pady = 10)
v1 = StringVar
v2 = StringVar
v3 = StringVar

def test(content):
    if content.isdigit():
        return True
    else:
        return False

testCMD = root.register(test)
Entry(frame,textvariable = v1, width = 10, validate = "key",\
      validatecommand = (testCMD,'%P')).grid(row=0,column =0)
Label(frame,text = "+").grid(row = 0, column =1)
Entry(frame,textvariable = v2, width = 10, validate = "key",\
      validatecommand = (testCMD,'%P')).grid(row=0,column =2)
Label(frame,text = "=").grid(row = 0, column =3)
Entry(frame,textvariable = v1, width = 10, validate = "key",\
      validatecommand = (testCMD,'%P')).grid(row=0,column =4)

def calc():
    result = int(v1.get()) + int(v2.get())
    v3.set(result)

Button(frame,text ="jisuanjieguo",command = calc).grid(row=1,column=2,pady=5)

mainloop()

#TODO get（）， 为什么会提示少一个参数啊！！！！！！！

报错信息如下：
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\Ataway\AppData\Local\Programs\Python\Python37-32\lib\tkinter__init__.py", line 1705, in call
return self.func(*args)
File "D:/py/AboutExcel/Tkinter_9_Entry_5_计算器.py", line 26, in calc
result = int(v1.get()) + int(v2.get())
TypeError: get() missing 1 required positional argument: 'self'

你这程序里有两个错误
第1，应该这么写

v1 = StringVar()
v2 = StringVar()
v3 = StringVar()

v1 = StringVar()这么写表示新建一个变量；
v1 = Stringvar表示将类型直接赋给v1

第2，你最后一个输入库应该绑定变量V3，你输成V1了

创建对象那里少了括号，我原来也碰到过