Displaying text when a button is clicked in python -

here create 9 buttons , when button clicked hello must displayed on button....i know simple i'm not getting did wrong.thanks in advance. here's code

from tkinter import * class design: def __init__(self):     self.button={}     self.root=tk()     self.root.title("simple design")     self.root.geometry("300x300")     in range(3):         j in range(3):             self.button[i,j]=button(self.root,text="*",padx=12,pady=12).grid(row=i,column=j)      self.click()    def click(self):     in range(3):         j in range(3):             handler=lambda i,j:self.update(i,j)             print "click function"             self.button[i,j]=button(self.root,command=handler)  def update(self,i,j):     self.button[i,j]=button(self).grid()     self.button[i,j]["text"]="hello"     print "hello" 

right can't test code, see problem here: self.button[i,j]=button(self.root,text="*",padx=12,pady=12).grid(row=i,column=j)! calling .grid(), has no return. self.button[i,j] none!

just in 2 lines: self.button[i,j]=button(self.root,text="*",padx=12,pady=12) , self.button[i,j].grid(row=i,column=j)