Off topic:tkinter window doesn't appear on Visual Studio for Mac

Question

[caro-ca]

I am practicing classes with GUI and tkinter on Visual Studio for Mac. My piece of code is:

#!/usr/bin/env python3
import tkinter as tk

class AddGUI (tk.Frame):
    def __init__ (self):   
        tk.Frame.__init__(self)
        self.master.title('adding one')
        self.define_widgets()
        self.grid()   

my_gui = AddGUI()
my_gui.mainloop()

When I run this script as python3 Tutoriol_Gui.py the script doesn't retrieve anything until I interrupt it meaning that the library is there but I don't know what to do to speed up the process or if something is missing.

$ python3 Tutoriol_Gui.py  ^X^C Traceback (most recent call last):   File "Tutoriol_Gui.py", line 15, in <module>
    my_gui.mainloop()   File "/Users/cacabezas/miniconda3/lib/python3.7/tkinter/__init__.py", line 1283, in mainloop
    self.tk.mainloop(n) KeyboardInterrupt (base)

Additionally, if I run:

#!/usr/bin/env python3  
import tkinter as tk 
root = tk.Tk()
root.mainloop()

I got retrieved a window

I hope you could help me out. I already checked different websites but couldn't find anything useful. Thank you in advance.