TclError：错误的#args错误

我不知道出了什么问题，但我一直都是这样

Tkinter回调中的异常回溯（最近一次调用最后一次）：文件“/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/lib-tk/Tkinter.py”，第1410行，在回调自我中.func（* args）文件“/ Users / Zane / Desktop / Factorial GUI.py”，第72行，在reveal2 self.text2.insert（0.0，message）文件“/Library/Frameworks/Python.framework/Versions/7.3 /lib/python2.7/lib-tk/Tkinter.py“，第2986行，插入self.tk.call（（self._w，'insert'，index，chars）args）TclError：错误#args：应该是“.22186144.22187184插入索引字符？tagList chars tagList ...？”

这是我的代码：`

from Tkinter import*

class App(Frame):

def fac(self, n):

    if n >= 0:
        if n == 1 or n == 0:
            return 1
        else:
            return n*self.fac(n-1)
    else:
        print('Error')

def per(self, n, r):

    y = (self.fac(n)) / self.fac(n - r)
    print (y)


def __init__(self, master):

    Frame.__init__(self,master)
    self.grid()
    self.create_widgets()

def create_widgets(self):
    self.instruction1 = Label(self, text = "Factorial:")
    self.instruction1.grid(row = 0, column = 0, columnspan = 1, sticky = W)

    self.password1 = Entry(self)
    self.password1.grid(row = 0, column = 1, sticky = W)

    self.submit_button1 = Button(self, text ="Enter", command = self.reveal1)
    self.submit_button1.grid(row = 2, column = 0, sticky = W)

    self.text1 = Text(self, width = 30, height = 1, wrap = WORD)
    self.text1.grid(row = 3, column = 0, columnspan = 2, sticky = W)

    self.instruction2 = Label(self, text = "Permutation:")
    self.instruction2.grid(row = 4, column = 0, columnspan = 1, sticky = W)

    self.password2 = Entry(self)
    self.password2.grid(row = 4, column = 1, sticky = W)

    self.password3 = Entry(self)
    self.password3.grid(row = 6, column = 1, sticky = W)

    self.submit_button2 = Button(self, text ="Enter", command = self.reveal2)
    self.submit_button2.grid(row = 7, column = 0, sticky = W)

    self.text2 = Text(self, width = 30, height = 1, wrap = WORD)
    self.text2.grid(row = 8, column = 0, columnspan = 2, sticky = W)

def reveal1(self):

    y = int(self.password1.get())

    message = self.fac(y)

    self.text1.delete(0.0, END)
    self.text1.insert(0.0, message)

def reveal2(self):

    y = int(self.password2.get())
    z = int(self.password3.get())

    message = self.per(y, z)

    self.text2.delete(0.0, END)
    self.text2.insert(0.0, message)


root = Tk()
root.title('Factorial')
root.geometry("340x300")
app = App(root)

root.mainloop()

`