Я пишу секундомер на питоне, но что-то не работает

Вот Код

from tkinter import *
from datetime import datetime

temp = 0
after_id = ' '

def tick():
global temp, after_id
after_id = root.after(1000, tick)
f_temp = datetime.utcfromtimestamp(temp).strftime('%M:%S')
label1.configure(text=str(f_temp))
temp += 1

def start_sw():
btn1.grid_forget()
btn2.grid(row=1, columnspan=2, sticky="ew")
tick()



def stop_sw():
btn2.grid_forget()
btn3.grid(row=1, column=0, sticky="ew")
btn4.grid(row=1, column=1, sticky="ew")
root.after_cancel(after_id)



def continue_sw():
btn3.grid_forget()
btn4.grid_forget()
btn2.grid(row=1, columnspan=2, sticky="ew")
tick()

def reset_sw():
global temp
temp = 0
label1.configure(text="00:00")
btn3.grid_forget()
btn4.grid_forget()
btn1.grid(row=1, columnspan=2, sticky="ew")
tick()


root = Tk()

root.title("StopWatch")

label1 = Label(root, width=5, font=("Ubuntu", 100), text="00:00")
label1.grid(row=0, columnspan=2)

btn1 = Button(root, text="Apasa START", font=("Ubuntu", 30), command=start_sw)
btn2 = Button(root, text="Apasa STOP", font=("Ubuntu", 30), command=stop_sw)
btn3 = Button(root, text="Apasa CONTINUE", font=("Ubuntu", 30), command=continue_sw)
btn4 = Button(root, text="Apasa RESET", font=("Ubuntu", 30), command=reset_sw)

btn1.grid(row=1, columnspan=2, sticky="ew")
root.mainloop()

Ошибка

File "C:/Users/AOGG/PycharmProjects/sek/sek.py", line 13
temp += 1
^ IndentationError: unindent does not match any outer indentation level