code: def forward(self, x: Tensor):
      assert x.ndim == 3
      x = (x - x.mean(-1, keepdim=True)) / x.std(-1, keepdim=True)
      x = self.weight * x + self.bias
      return x
  
imports: from typing import List, Optional
  import torch
  from torch import Tensor, nn
  from ..constants import CATEGORICAL, FEATURES, LABEL, LOGITS, NUMERICAL
  from .custom_transformer import CLSToken, Custom_Transformer, _TokenInitialization
  from .utils import init_weights
label_desc: Use image node_id 2 for calling the NLayerNorm obj's underlying member method code with example usage: obj.forward(x) and returns: x