Проблема в работе Калькулятора на Python.Нужен Совет⁠⁠

Создала калькулятор

Вот его начинка:

from tkinter import*

me=Tk()

me.geometry("354x460")

me.title("CALCULATOR")

melabel = Label(me,text="CALCULATOR",bg='White',font=("Times",30,'bold'))

melabel.pack(side=TOP)

me.config(background='Dark gray')

textin=StringVar()

operator=""

def clickbut(number): #lambda:clickbut(1)

global operator

operator=operator+str(numbers)

textin.set(operator)

def equlbut():

global operator

add=str(eval(operator))

textin.set(add)

operator=''

def equlbut():

global operator

sub=str(eval(operator))

textin.set(sub)

operator=''

def equlbut():

global operator

mul=str(eval(operator))

textin.set(mul)

operator=''

def equlbut():

global operator

div=str(eval(operator))

textin.set(div)

operator=''

def clrbut():

textin.set('')

metext=Entry(me,font=("Courier New",12,'bold'),textvar=textin,width=25,bd=5,bg='powder blue')

metext.pack()

but1=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(1),text="1",font=("Courier New",16,'bold'))

but1.place(x=10,y=100)

but2=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(2),text="2",font=("Courier New",16,'bold'))

but2.place(x=10,y=170)

but3=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(3),text="3",font=("Courier New",16,'bold'))

but3.place(x=10,y=240)

but4=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(4),text="4",font=("Courier New",16,'bold'))

but4.place(x=75,y=100)

but5=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(5),text="5",font=("Courier New",16,'bold'))

but5.place(x=75,y=170)

but6=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(6),text="6",font=("Courier New",16,'bold'))

but6.place(x=75,y=240)

but7=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(7),text="7",font=("Courier New",16,'bold'))

but7.place(x=140,y=100)

but8=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(8),text="8",font=("Courier New",16,'bold'))

but8.place(x=140,y=170)

but9=Button(me,padx=14,pady=14,bd=4,bg='white',command=lambda:clickbut(9),text="9",font=("Courier New",16,'bold'))

but9.place(x=140,y=240)

При запуске есть окно,но при вычислениях показывает ошибку.Почему?