code: def normalize(self, x):
      if not self.use_normalization:
          return x
  
      if self.mean_tensor is None:
          self.mean_tensor = Variable(
              self.mean.view(1, 3, 1, 1).expand(x.shape),
              requires_grad=False,
          )
          self.std_tensor = Variable(
              self.std.view(1, 3, 1, 1).expand(x.shape),
              requires_grad=False,
          )
  
      x = (x + 1) / 2
      return (x - self.mean_tensor) / self.std_tensor
  
file_path: BigDL/python/nano/client-application/VideoStylization/feature_model.py
imports: import torch
  import torch.nn
  from torch.autograd import Variable
  from torchvision import models
label_desc: Use image node_id 2 for calling the FeaturesNet obj's underlying member method code with example usage: obj.normalize(x) and returns: unknown, x