code: def detect(self, img):
      # initialize our list of keypoints
      kps = []
  
      # loop over the height and with of the image, taking a `step`
      # in each direction
      for x in range(0, img.shape[1], self.step):
          for y in range(0, img.shape[0], self.step):
              # create a keypoint and add it to the keypoints list
              kps.append(cv2.KeyPoint(x, y, self.radius))
  
      # return the dense keypoints
      return kps
  
imports: import cv2
label_desc: Use image node_id 2 for calling the DENSE obj's underlying member method code with example usage: obj.detect(img) and returns: kps