why this code loop forever after a draw a rectangle

[Joonas Liik]

On 16 September 2016 at 14:24, meInvent bbird <jobmattcon at gmail.com> wrote:
> im = img.copy()
> cntcounter = 0
> for cnt in contours:
>         epsilon = 0.1*cv2.arcLength(cnt,True)
>         approx = cv2.approxPolyDP(cnt,epsilon,True)
>         #peri = cv2.arcLength(cnt, True)
>         #approx = cv2.approxPolyDP(c, 0.5 * peri, True)
>         #print("len(approx)="+str(len(approx)))
>         if len(approx) == 4:
>             print("approx=" + str(approx))
>             cntcounter = cntcounter + 1
>             print("here1")
>             x,y,w,h = cv2.boundingRect(cnt)
>             print("here2")
>             while im is None:
>                 time.sleep(1)
>             if im is not None:
>                 print("here3")
>                 im = cv2.rectangle(im.copy(), (x,y), (x+w, y+h), (0,255,0), 2)
>                 #im = cv2.line(im,(x,y),(x+w,y),(0,255,0),2)
>                 #im = cv2.line(im,(x+w,y),(x+w,y+h),(0,255,0),2)
>                 #im = cv2.line(im,(x,y+h),(x+w,y+h),(0,255,0),2)
>                 #im = cv2.line(im,(x,y),(x,y+h),(0,255,0),2)
>
>
> cv2.imwrite(r'C:\Users\tester\Documents\masda.png',im)
> --
> https://mail.python.org/mailman/listinfo/python-list

not sure but..  this bit reads really suspicious:

            while im is None:
                time.sleep(1)

if im is ever None then how will it ever become not None? unless there
is some other thread at work i can't really see this happening.
and if there is some other thread at work then there is probably some
better solution than sleep()