title: Want to find contours -> ValueError: not enough values to unpack (expected 3, got 2), this appears
body: <p>My simple Python code is this</p>
  <pre><code>import cv2
  
  img=cv2.imread('Materials/shapes.png')
  
  blur=cv2.GaussianBlur(img,(3,3),0)
  gray=cv2.cvtColor(blur,cv2.COLOR_BGR2GRAY)
  returns,thresh=cv2.threshold(gray,80,255,cv2.THRESH_BINARY)
  
  ret,contours,hierachy=cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
  
  for cnt in contours:
  
      area=cv2.contourArea(cnt) #contour area
      
      if (area&gt;1220):
          cv2.drawContours(img,[cnt],-1,(0,255,0),2)
          cv2.imshow('RGB',img)
          cv2.waitKey(1000)
          print(len(cnt))
  
  import numpy as np
  
  contours=np.array(contours)
  
  print(contours)
  </code></pre>
  <p>This worked fine. But recently without me even making any changes. This was throwed to me</p>
  <blockquote>
  <p>ret,contours,hierachy=cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)</p>
  <p>ValueError: not enough values to unpack (expected 3, got 2)</p>
  </blockquote>