为什么symmetryAxisFlag的变量值不会改变？

def createQuadraticFunction(self):
        self.root3 = Tk()
        self.root3.resizable(0, 0)
        self.root3.title("Quadratic Function")
        valueA = Entry(self.root3, width=10)
        valueA.grid(row=1, column=1, sticky=W)
        valueB = Entry(self.root3, width=10)
        valueB.grid(row=2, column=1, sticky=W)
        valueC = Entry(self.root3, width=10)
        valueC.grid(row=3, column=1, sticky=W)
        symmetryAxisFlag = IntVar()
        isDrawSymmetryAxis = Checkbutton(
            self.root3, text="绘制对称轴", variable=symmetryAxisFlag, onvalue=1, offvalue=0)
        isDrawSymmetryAxis.grid(row=4, column=0, columnspan=2)
        Label(self.root3, text="绘制y=ax^2+bx+c的函数", font=("Arial", 20)
              ).grid(row=0, column=0, columnspan=2)
        Label(self.root3, text="a=", font=("Arial", 15)).grid(
            row=1, column=0, sticky=E)
        Label(self.root3, text="b=", font=("Arial", 15)).grid(
            row=2, column=0, sticky=E)
        Label(self.root3, text="c=", font=("Arial", 15)).grid(
            row=3, column=0, sticky=E)
        def quadraticFunction(): return self.drawQuadraticFunction(
            valueA.get(), valueB.get(), valueC.get(), symmetryAxisFlag.get())
        drawFunction = Button(self.root3, text="生成函数", command=quadraticFunction).grid(
            row=5, column=0, columnspan=2)