how to end the tkinter program

[mangle200]

i have a set of code for a gui that runs using a dictionary but i cant get the code to exit once the user presses the last button named end

import sys
import tkinter as tk
from functools import partial
class Situation(tk.Frame):

    def __init__(self, master=None, story='', buttons=[], **kwargs):
        tk.Frame.__init__(self, master, **kwargs)

        story_lbl = tk.Label(self, text=story, justify=tk.LEFT, anchor=tk.NW, font=("Play", 10))
        story_lbl.pack()

        for btn_text, new_situation in buttons:
            btn = tk.Button(self, text=btn_text, command=partial(self.quit_, new_situation),padx=10, pady=10)
            btn.pack()








    def quit_(self, new_situation):
        self.destroy()
        load(new_situation)

def load(situation=None):
    frame = Situation(root, **SITUATIONS.get(situation))
    frame.pack()
SITUATIONS = {

    None:{
        'story':
"""
true or false

Tristan has 80+ subscribers?
""",
'buttons':[
    ('true','Correct'),
    ('false','incorrect')

    ],
    },
    'Correct':{
       'story':
"""
question 1=correct

question 2
tristan's youtube channel name is what?
""",
'buttons':[
    ('mangle200','correct1'),
    ('Tristan Lauzon','incorrect1'),
    ('Winter Wolf','incorrect1')
    ],
        },
    'incorrect':{
        'story':
"""
question 1 = incorrect
question 2
tristan's youtube channel name is what?

""",

'buttons':[
    ('mangle200','correct1.1'),
    ('Tristan Lauzon','incorrect1.1'),
    ('Winter Wolf','incorrect1.1')
    ],
        },
    'correct1':{
        'story':
"""
question 1 = correct
question 2 = correct
""",
'buttons':[
    ('end')
    ],
        },
    'correct1.1':{
        'story':
"""
question 1 = incorrect
question 2 = correct
""",
'buttons':[
    ('end')
    ],
        },
    'incorrect1':{
        'story':
"""
question 1 = correct
question 2 = incorrect

""",
'buttons':[
    ('end')
    ],
        },
    'incorrect1.1':{
        'story':
"""
question 1 = incorrect
question 2 = incorrect
""",
'buttons':[
    ('end')
    ],
        },
    }

def beginning():
    start_button.destroy()
    load() # load the first story

#WINDOW
root = tk.Tk()
root.geometry('500x500-500-300')
root.title('multiple choice quiz')
root.attributes('-fullscreen', True)
#START
start_button = tk.Button(root, text="START", command=beginning)
start_button.place(relx=.5, rely=.5, anchor='c')


#THE LOOP
root.mainloop()

[rproffitt]

I'll skip reading over 100 lines and noted this from the past.

Read https://www.daniweb.com/programming/software-development/threads/66698/exit-a-tkinter-gui-program