Getting a variable out of an Entry text zone

Question

I'm coding an Ip Calculator to train with Python and Tkinter. As far as I am, I managed to create a UI with a text zone in which the user will write their IP. When they press the OK button, the IP is assigned to the ip_addr var, I tried to print it and it seems to work.

But when I try to use it to display netmask or network it seems my var is nowhere to be found. How can I retrieve this variable to display result in a second text zone, using the second piece of code (don't mind the print() in it, I will properly embed it in Label and Frame later)

import ipaddress
### For Tkinter import problem
try:
    from Tkinter import *
except ImportError:
    from tkinter import *

def ok_env():
    ip_addr = zone_text.get()
    #zone_text.delete(0,END)
    print(ip_addr) #La variable est bien recuperée quand on clique sur le bouton ok, mais pas transferée?

ipcalc_window = Tk()
ipcalc_window.title("IP Calculator")
ipcalc_window.geometry('768x512')
ipcalc_window.minsize(768, 512)
ipcalc_window.config(background='#C5D0DB')

ipcalc_mainframe = Frame(ipcalc_window, bg='#C5D0DB')
ipcalc_subframe = Frame(ipcalc_window, bg='white')

label_title = Label(ipcalc_mainframe, text="Entrez l'adresse IP, au format XXX.XXX.XXX.XXX/XX:", bg='#C5D0DB', font=('Consolas', 16))
label_title.pack(pady=5)

zone_text = Entry(ipcalc_mainframe, width=45, bg='white', font=('Consolas', 16))
zone_text.pack()

ok_button = Button(ipcalc_mainframe, text="OK", font=('Consolas', 16), command=ok_env)
ok_button.pack(pady=5)

label_text = Label(ipcalc_subframe, font=('Consolas', 16) )
label_text.pack()

ipcalc_mainframe.pack()
ipcalc_subframe.pack()

ipcalc_window.mainloop()

### Piece of code not working
info4 = ipaddress.ip_interface(ip_addr)
print("> [+] IP:", ip_addr, "\n> [+]")
print("> [+] Addresse Reseau:", info4.network)

Hope my English is not to bad, thanks to those who will take the time to read it.