how to spawn a message box in tkinter code example

Example: list in tkinter messagebox

from tkinter import *
from tkinter import messagebox

def listMessageBox(arr):
  window=Tk()
  listbox=Listbox(window)
  listbox.pack(fill=BOTH, expand=1) #adds listbox to window
  [listbox.insert(END, row) for row in arr] #one line for loop
  window.mainloop()
  
arr=['a','b','c','1','2','3']

listMessageBox(arr)