code: def pre_func(self, i, fields="qkv", l=0):
      layer = self.layers[i]
  
      def func(nodes):
          x = nodes.data["x"]
          norm_x = (
              layer.sublayer[l].norm(x) if fields.startswith("q") else x
          )
          if fields != "qkv":
              return layer.src_attn.get(norm_x, fields)
          else:
              return layer.self_attn.get(norm_x, fields)
  
      return func
  
imports: from .config import *
  from .act import *
  from .attention import *
  from .viz import *
  from .layers import *
  from .functions import *
  from .embedding import *
  import threading
  import dgl.function
  import torch
  import torch.nn.init
label_desc: Use image node_id 2 for calling the Decoder obj's underlying member method code with example usage: obj.pre_func(i, fields, l) and returns: func, layer, layer