class_docstr: Class for extracting activations and
  registering gradients from targeted intermediate layers 
code: def save_activation(self, module, input, output):
      activation = output
      if self.reshape_transform is not None:
          activation = self.reshape_transform(activation)
      self.activations.append(activation.cpu().detach())
  
imports: import cv2
  import numpy
label_desc: Use image node_id 2 for calling the ActivationsAndGradients obj's underlying member method code with example usage: obj.save_activation(module, input, output) without return types