python - Why does this code work only with *args in something()? -

would mind taking minute explain why code works when give something() parameter *args? seems though should work without because being called without arguments... stumped..

from tkinter import *  mgui = tk() mgui.geometry('570x130+700+200') mgui.resizable(width = false, height = false) mgui.title('title')  def something(*args):         if somevalue.get() == 'tom':             mlabel2.lift()         else:             mlabel2.lower()  mylist = ['henry', 'tom', 'phil'] somevalue = stringvar() somevalue.trace('w', something)  mlabel = label(text = '  name:') mlabel.grid(row = 0, column = 0, sticky = e) mlabel2 = label(text = 'success') mlabel2.grid(row = 0, column = 0, sticky = e) mlabel2.lower()  somemenu = optionmenu(mgui, somevalue, *mylist) somemenu.grid(row = 0, column = 1, sticky = w) somemenu.config(width = 14, anchor = w)  mgui.mainloop() 

**edit, program initialize, select value somemenu throws out typeerror: something() takes no arguments (3 given)

the callback function trace called 3 argument: name1, name2, op according tcl trace documentation.

so callback function should following form:

def callback(name1, name2, op):     pass 

but, in question code, something not use of parameters. function use abitrary argument list (*args) implicitly ignore them.