Why does jupyter kernel keep dying?

I am trying to run this code. But when I run this code my jupyter kernel keeps dying and doesn't restart.

Code:

import tkinter
import pyperclip
from tkinter import *
win = Tk()
win.geometry('700x350')
my_clip = Text(win, height=15)
my_clip.pack
def update_text():
    global my_clip
my_clip.insert(END,pyperclip.paste())

button=Button(win, text="Paste Here",  command=update_text)
button.pack()
win.mainloop()