Animation4

Grow or shrink your shapes
Remember to make this work this would need to be inside canvas code with mainloop at bottom

a=150 #create simple variables to put coordinates in
b=150
c=200
d=200
blob2=win.create_rectangle(a,b,c,d, fill="red") #use variables in place of coordinates
for i in range(60):
    a=a-1 #takes one away from coordinate variable a at top
    b=b-1 #takes one away from coordinate variable b at top
    win.coords(blob2, a,b,c,d) #redraws the shape using the numbers inside the variables
    tk.update() #updates the canvas
    time.sleep(0.05)
#short time delay

Challenges
Grow or shrink a shape by using variables