Не могу найти проблему

from tkinter import *
from decimal import *
 
 
root = Tk()
root.title("Calculator for brat")
 
button = ([
    "1", "2", "3", "4",
    "5", "6", "7", "8",
    "9", "0", "+", "-",
    "*", "/", ".", "C", "=",])
 
numStr = ''
stack = []
def calculate():
    global stack
    global label
    result = 0
    operand2 = Decimal(stack.pop())
    operation = stack.pop()
    operand1 = Decimal(stack.pop())
 
    if operation == '+':
        result = operand1 + operand2
    if operation == '-':
        result = operand1 - operand2
    if operation == '/':
        result = operand1 / operand2
    if operation == '*':
        result = operand1 * operand2
    label.configure(text=str(result))
 
 
def click(text):
    global activeStr
    global stack
    if text == 'CE':
        stack.clear()
        numStr = ''
        label.configure(text = '0')
    elif '0' <= text <= '9':
        activeStr += text
        label.configure(text = numStr)
    elif text == '.':
        if activeStr.find('.') == -1:
            activeStr += text
            label.configure(text = numStr)
    else:
        if len(stack) >= 2:
            stack.append(label['text'])
            calculate()
            stack.clear()
            stack.append(label['text'])
            numStr = ''
            if text != '=':
                stack.append(text)
        else:
            if text != '=':
                stack.append(label['text'])
                stack.append(text)
                activeStr = ''
                label.configure(text = '0')
 
 
label = Label(root, text = '0', width = 35)
label.grid(row = 0, column = 0, columnspan = 3, sticky="nsew")
 
button = Button(root, text ='CE', command = lambda text = 'CE': click(text))
button.grid(row = 1, column = 3, sticky = "nsew")
for row in range(4):
    for col in range(4):
        button = Button(root, text = button[row][col],
            command = lambda row = row, col = col: click(buttons[row][col]))
        button.grid(row = row + 2, column = col, sticky = "nsew")
 
root.grid_rowconfigure(6, weight=1)
root.grid_columnconfigure(3, weight=1)
 
root.mainloop()

Traceback (most recent call last):
  File "C:/Users/aandreykin/AppData/Local/Programs/Python/Python37-32/321.py", line 73, in <module>
    button = Button(root, text = button[row][col],
  File "C:\Users\aandreykin\AppData\Local\Programs\Python\Python37-32\lib\tkinter\__init__.py", line 1489, in cget
    return self.tk.call(self._w, 'cget', '-' + key)
TypeError: can only concatenate str (not "int") to str