code: def _layer_norm(self, name, x):
      
      if self.init_layers:
        bn = LayerNorm()
        bn.name = name
        self.layers += [bn]
      else:
        bn = self.layers[self.layer_idx]
        self.layer_idx += 1
      bn.device_name = self.device_name
      bn.set_training(self.training)
      x = bn.fprop(x)
      return x
docs: Layer normalization.