What is the role of underscore in assigning variable process (python)

I have trouble with understanding the role of the underscore in last line of below code. I've read that functions of _ consists of storing last expression, but can be used as well to omit certain values. I don't now why it is used here. Thank You in advance for help

I found this thread, which was helpful with understanding of functions which _ can fulfill, but I still don't know in which way it was used in this code: What is the purpose of the single underscore "_" variable in Python?

@staticmethod  
def frames():  
  camera = cv2.VideoCapture(Camera.video_source)  
  if not camera.isOpened():  
    raise RuntimeError('Could not start camera.')  
  while True:  
  # read current frame  
    _, img = camera.read() #Obtain images captured by the camera

Read more here: https://stackoverflow.com/questions/67011573/what-is-the-role-of-underscore-in-assigning-variable-process-python