How to use gui.update_idletasks() in CustomTkinter

[Barry-sze]

def StartProgress():
for i in range(5):
progress_var['value'] += 20
stringvar.set(progress_var['value'])
# get the value
label.config(text=stringvar.get()+' %')
# update value
gui.update_idletasks()
time.sleep(1)