from tkinter import *
 
class Butterfly:
     def __init__(self, width=500, height=500, size=100):
          self.width=width
          self.height=height
          self.size=size
          self.canv=Canvas(root, width=self.width, height=self.height)
          self.canv.pack()
          self.x1=self.width/2-self.size/2
          self.y1=self.height/2-self.size/2
          self.x2=self.width/2+self.size/2
          self.y2=self.height/2+self.size/2
          self.canv.create_polygon(self.x1, self.y1, self.x2, self.y2, self.x2, self.y1, self.x1, self.y2,
                                     tag="butterfly", fill="light grey", outline="black", width=1)
     def move_right(self, key):
          self.canv.move("butterfly", key, 0)

 from butterfly import *
butt=Butterfly(400, 400, 50)
butt.move_right(200)

 Traceback (most recent call last):
  File "/media/yevhenii/8E24F95024F93BB1/Users/Yevhenii-PC-Windows/Desktop/butterfly.py", line 24, in <module>
    butt.move_right(200)
  File "/media/yevhenii/8E24F95024F93BB1/Users/Yevhenii-PC-Windows/Desktop/butterfly.py", line 20, in move_right
    self.canv.move("butterfly", key, 0)
  File "/usr/lib/python3.5/tkinter/__init__.py", line 2434, in move
    self.tk.call((self._w, 'move') + args)
_tkinter.TclError: invalid command name ".3070977548"

 class Butterfly:
     def __init__(self, width=500, height=500, size=100):
      .....
          self.canv=Canvas(root, width=self.width, height=self.height)
     .....

 root = Tk()

 сlass Butterfly:
     def __init__(self, root, width=500, height=500, size=100):
          ....
          self.canv=Canvas(root, width=self.width, height=self.height)
          ....

 from tkinter import *
from butterfly import *
root = Tk()
butt = Butterfly(root, 400, 400, 50)
butt.move_right(100)
root.mainloop()