new_contents: import numpy as np
  import cv2
  
  # Create a black image
  img = np.zeros((512, 512, 3), np.uint8)
  
  # Draw a diagonal blue line with thickness of 5 px
  cv2.line(img,(0,0),(511,511),(255,0,0),5)
  
  cv2.imshow("line", img)
  
  key = cv2.waitKey(0)
  cv2.destroyAllWindows()
subject: Add draw line example