Messagebox

[menator01]

Here is an example of your code modified

from tkinter import messagebox

def func():
    while True:
        data = input('enter a, b, or c. To quit enter q\n>> ')
        if data == 'a':
            data = 5
        elif data == 'b':
            data = 10
        elif data == 'c':
            data = 15
        elif data == 'q':
            print('Goodbye!')
            break
        else:
            messagebox.showerror(title='Error', message='Wrong Input')
            data = 0
        print(f'data was set to {data}\n')
    
func()