code: def __call__(self, data):
      keypoints_idx = torch.randint(
          0, data.pos.shape[0], (self.num_points,)
      )
      data.keypoints = keypoints_idx
      return data
  
imports: import torch
label_desc: Use image node_id 2 for calling the RandomDetector obj's underlying member method code with example usage: obj.__call__(data) and returns: data