code: def get_ref_batch(self, ref_batch):
      return self.ref_features[ref_batch]
  
imports: from .inception_v3 import InceptionV3
  import blobfile
  import torch
  import torch.distributed
  import torch.nn
  from cm import dist_util
  import numpy
  import warnings
  from scipy import linalg
  from PIL import Image
  from tqdm import tqdm
label_desc: Use image node_id 9 for calling the FIDAndIS obj's underlying member method code with example usage: obj.get_ref_batch(ref_batch) and returns: self