How to get and save checkboxs names in a list with tkinter, python 3.6.5

I would like to to use tkinter and checkboxs to make a selection of files in a directory and save those files names in a list when I press a button :

import speech_recognition as sr
import playsound
import os
import glob
import unidecode
import pickle
import random
import tkinter
from tkinter.constants import *

ldv=os.listdir("D:/FFOutput/")
i=0
ldv1=[]
while i<len(ldv):
    ldv1.append(unidecode.unidecode(ldv[i]))
    i=i+1
print(ldv1)

tk = tkinter.Tk()
frame = tkinter.Frame(tk, relief=RIDGE, borderwidth=10)
frame.pack(fill=BOTH,expand=1)
label = tkinter.Label(frame, text="choose file(s)")
label.pack(fill=X, expand=1)


a=0
while a<len(ldv1):
    bouton=tkinter.Checkbutton(tk, text=ldv1[a], command=print(ldv1[a]))
    a=a+1
    bouton.pack()

button = tkinter.Button(frame,text="Exit",command=tk.destroy)
button.pack(side=BOTTOM)

lr=[]

buttonregister = tkinter.Button(tk,text="Register checked files names in list lr and close tk")
buttonregister.pack(side=BOTTOM)

print(lr)

tk.mainloop()

When i click on buttonregister i would like to append files names in the list lr and close the frame.

Exemple : enter image description here In that exemple, I wish to print(lr) "['alors soyez pret.mp3','c'est bien.mp3'] in the shell when i click on the button.

Thank you