How to use `cv2.findContours` in different OpenCV versions?

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An alternative to work with 2.x 、3.x、4.x is:

cnts, hiers = cv2.findContours(...)[-2:]

Notice:

cv2.findContours has changed since OpenCV 3.x, but in OpenCV 4.0 it changes back!!!

In OpenCV 3.4:

findContours(image, mode, method[, contours[, hierarchy[, offset]]]) -> image, contours, hierarchy

enter image description here

In OpenCV 4.0:

findContours(image, mode, method[, contours[, hierarchy[, offset]]]) -> contours, hierarchy

enter image description here

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