Tkinter Калькулятор

from tkinter import *
from tkinter import messagebox
from tkinter import ttk
import math
import sys
 
root = Tk()
root.title("Calculator")
 
bttn_list = [
"7", "8", "9", "+", "*", 
"4", "5", "6", "-", "/",
"1", "2", "3",  "=", "x ** n",
"0", ".", "±",  "C",
"Exit", "π", "sin", "cos",
"(", ")","n!","√2", ]
 
r = 1
c = 0
for i in bttn_list:
    rel = ""
    cmd = lambda x = i: calc(x)
    tkk.Button(root, text=i, commad = cmd, width = 10).grid(row = r, collum = c)
    c += 1
    if c > 4:
        c = 0
        r += 1
 
calc_entry = Entry(root, width = 33)
calc_entry.grid(row = 0, collum = 0, collumspan = 5)
 
 
#логика калькулятора
def calc(key):
    global memory
    if key == "=":
#исключения написания слов
        str1 = "-+0123456789.*/)("
        if calc_entry.get()[0] not in str1:
            calc_entry.insert(END, "First symbol is not number!")
            messagebox.showerror("Error!", "You did not enter the number!")
#исчисления
        try:
            result = eval(calc_entry.get())
            calc_entry.insert(END, "=" + str(result))
        except:
            calc_entry.insert(END, "Error!")
            messagebox.showerror("Error!", "Check the correctness of data")
 
#очищение поля ввода
    elif key == "C":
        calc_entry.delete(0, END)
 
#функция изменения минуса на плюс
    elif key == "±"
        if "=" in calc_entry.get():
            calc_entry.delete(0, END)
        try:
            if calc_entry.get()[0] == "-":
                calc_entry.delete(0)
            else:
                calc_entry.insert(0, "-")
        except IndexError:
            pass
 
#число пи
elif key == "π":
        calc_entry.insert(END, math.pi)
 
#функция выхода из программы
elif key == "Exit":
    root.after(1, root.destroy)
    sys.exit
 
elif key == "x ** n":
    calc_entry.insert(END, "**")
 
elif key == sin:
    calc_entry.insert(END, "=" + str(math.sin(int(calc_entry.get()))))
elif key == "cos":
    calc_entry.insert(END, "=" + str(math.sin(int(calc_entry.get()))))
 
elif key == "(":
    calc_entry.insert(END, "(")
elif key == ")":
    calc_entry.insert(END, ")")
 
elif key == "n!":
    calc_entry.insert(END, "=" + str(math.factorial(int(calc_entry.get()))))
 
elif key == "√2":
        calc_entry.insert(END, "=" + str(math.sqrt(int(calc_entry.get()))))
 
else:
    if "=" in calc_entry.get():
        calc_entry.delete(0, END)
    calc_entry.insert(END, key)
 
 
root.mainloop()