code: def aggregate_multi_layers(self, cam_per_target_layer):
      cam_per_target_layer = np.concatenate(
          cam_per_target_layer, axis=1
      )
      cam_per_target_layer = np.maximum(cam_per_target_layer, 0)
      result = np.mean(cam_per_target_layer, axis=1)
      return self.scale_cam_image(result)
  
imports: import cv2
  import numpy
label_desc: Use image node_id 7 for calling the GradCAM obj's underlying member method code with example usage: obj.aggregate_multi_layers(cam_per_target_layer) and returns: self