def foo():
<>global x,cancel_flag,flag
<>if x<=0:
<><>flag=1
<>if x>270:
<><>flag=0
<>if flag:
<><>x=x+10
<>else:
<><>x=x-10
<>lab1.place(x=x,y=50)
<>if cancel_flag=False:
<><>root.after(200,foo)
def foo():
<>global x,cancel_flag,flag
<>if x<=0:
<><>flag=1
<>if x>270:
<><>flag=0
<>if flag:
<><>x=x+10
<>else:
<><>x=x-10
<>lab1.place(x=x,y=50)
<>if cancel_flag=False:
<><>root.after(200,foo)