how to get camera stream cv2

1import numpy as np
2import cv2
3
4cap = cv2.VideoCapture(0)
5
6while(True):
7    # Capture frame-by-frame
8    ret, frame = cap.read()
9
10    # Our operations on the frame come here
11    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
12
13    # Display the resulting frame
14    cv2.imshow('frame',gray)
15    if cv2.waitKey(1) & 0xFF == ord('q'):
16        break
17
18# When everything done, release the capture
19cap.release()
20cv2.destroyAllWindows()
21