class_docstr: Image extractor
  Args:
      image_model (str): image model
      finetune (bool): finetune
code: def forward(self, img):
      with torch.set_grad_enabled(self.finetune):
          feats = self.image_model.encode_image(img)
      return feats
  
imports: import torch
  from torch import nn
  from towhee.models import clip
label_desc: Use image node_id 2 for calling the ImageExtractor obj's underlying member method code with example usage: obj.forward(img) and returns: feats