Determine which version of OpenCV

>>> from cv2 import __version__
>>> __version__
'$Rev: 4557 $'

If that doesn't work then, use cv instead of cv2.

Convenient functions to check OpenCV version in run-time

def cv2():
    return opencv_version("2")

def cv3():
    return opencv_version("3")

def cv4():
    return opencv_version("4")

def opencv_version(version):
    import cv2
    return cv2.__version__.startswith(version)

Useful when performing cv2.findContours() since return signature varies by version

# Using OpenCV 2.X or OpenCV 4
if cv2() or cv4():
    cnts, _ = cv2.findContours(image, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

# Using OpenCV 3
elif cv3():
    _, cnts, _ = cv2.findContours(image, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

One line way can be like below:-