Как правильно создать класс и переместить кружок?

import random
import Tkinter as tk
 
screen_w = screen_h = 500
balls = []
 
class Ball(object):
 
    def __init__(self, x, y, color):
        self.x = x
        self.y = y
        self.radius = 50
        self.color = color
        
        x1, y1 = self.x - self.radius, self.y - self.radius
        x2, y2 = self.x + self.radius, self.y + self.radius
        canvas.create_oval(x1, y1, x2, y2, outline = color)
 
  
 
        def on_click(self, event): 
            z = random.randint(0, 500)
            w = random.randint(0, 500)
            canvas.coords(self, z, w)   
 
 
if __name__ == "__main__":
    root = tk.Tk()
    canvas = tk.Canvas(root, width=screen_w, height=screen_h)
    canvas.pack(fill = "both")
  #  canvas.bind("<1>", on_click)
 
    balls = [Ball(100, 100), Ball(200, 150), Ball(300, 200), \
             Ball(120, 450), Ball(400, 170)]     
 
    root.mainloop()

#!/usr/bin/env python
#coding: utf-8
 
import Tkinter as tk
 
 
class Simple():
  def __init__(self):
    self.root = tk.Tk()
    self.root.title('Simple example')
    self.root.geometry('400x500')
    self.canvas=tk.Canvas(self.root)
    self.text = self.canvas.create_text(30,20, text='simple text status', fill="white")
    self.circle = self.canvas.create_oval(200,200,50,50,fill='green')
    self.canvas.pack()
 
  def eventOn(self, event):
    self.canvas.itemconfigure(self.text, text=(event.x,':', event.y))
 
  def eventLeftClick(self, event):
    self.canvas.itemconfigure(self.circle, fill="red")
 
  def eventRightClick(self, event):
    self.canvas.itemconfigure(self.circle, fill="green")
 
  def run(self):
    self.canvas.tag_bind(self.circle,'<Motion>', self.eventOn)
    self.canvas.tag_bind(self.circle,'<Button-3>', self.eventRightClick)
    self.canvas.tag_bind(self.circle,'<Button-1>', self.eventLeftClick)
    self.root.mainloop()
 
s=Simple()
s.run()