change hostname through Tkinter app

change_hostname.desktop

[Desktop Entry]
Type=Application
Exec=python /home/robotuser/helper/change_hostname.py
Icon=/home/robotuser/Downloads/change.png # only if needed
Name=Change the hostname
Terminal=false

change_hostname.py

#!/usr/bin/python

from Tkinter import *

import subprocess


import tkMessageBox

master = Tk()
master.title('Change hostname')
e = Entry(master)
e.pack()

e.focus_set()

import socket

def hostname_resolves(hostname):
    '''this function checks if hostname already exists in the network'''
    try:
        socket.gethostbyname(hostname)
        return True
    except socket.error:
        return False



def callback():
''' callback from button press or enter on textarea'''
    if(e.get()!=""):
        name=e.get()
    else:
        return
    
    hostname_full=["hostnamectl","set-hostname",name]

    if(hostname_resolves(name)):
        tkMessageBox.showerror("Hostname exists","Hostname exists already in the network")
        return
    if(tkMessageBox.askyesno("Hostname changed",
                                "Do you want to change hostname to {}?".format(name))):
        
        subprocess.call(hostname_full)
        tkMessageBox.showinfo("Hostname changed", "Hostname changed to {}".format(name))
        master.destroy()
b = Button(master, text="change hostname", width=15, command=callback)
b.pack()
e.bind("<Return>", lambda x: callback())
mainloop()