Python TKInter close window -

i have homepage when click button, opens window. when close index , open first window, works out fine, when try open index first window, gives me error:

return_but["command"] = viewwindestroy attributeerror: 'function' object has no attribute 'destroy' 

here code:

return_but = button(app,text = "return home") return_but["command"] = viewwin.destroy() 

the function:

def viewwindestroy():      viewwin.destroy()