how to check how many cameras are connected to device in python 5c

1import cv2
2
3def clearCapture(capture):
4    capture.release()
5    cv2.destroyAllWindows()
6
7def countCameras():
8    n = 0
9    for i in range(10):
10        try:
11            cap = cv2.VideoCapture(i)
12            ret, frame = cap.read()
13            cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
14            clearCapture(cap)
15            n += 1
16        except:
17            clearCapture(cap)
18            break
19    return n
20
21print countCameras()
22