tkinter.messagebox.showinfo doesn't always work

messagebox, along with some other modules like filedialog, does not automatically get imported when you import tkinter. Import it explicitly, using as and/or from as desired.

>>> import tkinter
>>> tkinter.messagebox.showinfo(message='hi')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'messagebox'
>>> import tkinter.messagebox
>>> tkinter.messagebox.showinfo(message='hi')
'ok'
>>> from tkinter import messagebox
>>> messagebox.showinfo(message='hi')
'ok'