以下python代码如何修改才能正确执行?

问题遇到的现象和发生背景

import time

import tkinter as tk

import keyboard

st = tk.Tk()
st.geometry("500x300")

def bk():
st.destroy()

start_button = tk.Button(text='开始游戏', command=bk, font=(None, 15), width=10, heigh=3)
rule = tk.Label(text='开始后，按下空格键，\n等待3秒再按键，两次间隔等于3秒获胜', font=(None, 20))
rule.pack()
start_button.place(x=200, y=200)
tk.mainloop()
begin = tk.Tk()
begin.geometry("500x300")
t = tk.StringVar()

_time = tk.Label(textvariable=t, font=(None, 50))
_time.pack()
hd = False
ab = False

def do():
keyboard.clear_hotkey('space')
keyboard.add_hotkey('space', do_)
global t1
t1 = time.time()
begin_time = 3.00
begin_time = float(format(begin_time, ".2f"))
for i in range(300):
begin_time -= 0.01
begin_time = float(format(begin_time, ".2f"))
t.set(begin_time)
time.sleep(0.01)
if not hd:
lose = tk.Label(text='你失败了', font=(None, 50))
lose.pack()

def do_():
global t2
t2 = time.time()
if float(format(t1, ".2f")) - float(format(t2, ".2f")) == 3.00:
tk.Label(text='成功！', font=(None, 20)).pack()
else:
lose = tk.Label(text='你失败了', font=(None, 50))
lose.pack()
hd = True

keyboard.add_hotkey('space', do)

begin.mainloop()

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果

目前有什么错误现象啊

哪位大佬可以帮忙看看，这个代码的错误在什么的地方？如何修改？