Python: ValueError: too many values to unpack

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I'm writing an opencv program and I found a script on another stackoverflow question: Computer Vision Masking A Human Hand

I've already asked this question at Stackoverflow: OpenCV python: ValueError: too many values to unpack

When I run the scripted answer, I get the following error:

Traceback (most recent call last):
    File "skinimagecontour.py", line 13, in <module>
    contours, _ = cv2.findContours(skin_ycrcb, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
ValueError: too many values to unpack

The code:

import sys
import numpy
import cv2

im = cv2.imread('Photos/test.jpg')
im_ycrcb = cv2.cvtColor(im, cv2.COLOR_BGR2YCR_CB)

skin_ycrcb_mint = numpy.array((0, 133, 77))
skin_ycrcb_maxt = numpy.array((255, 173, 127))
skin_ycrcb = cv2.inRange(im_ycrcb, skin_ycrcb_mint, skin_ycrcb_maxt)
cv2.imwrite('Photos/output2.jpg', skin_ycrcb) # Second image

contours, _ = cv2.findContours(skin_ycrcb, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
for i, c in enumerate(contours):
    area = cv2.contourArea(c)
    if area > 1000:
        cv2.drawContours(im, contours, i, (255, 0, 0), 3)
cv2.imwrite('Photos/output3.jpg', im)

Any help is appreciated!