code: def append_name(name, postfix):
      if name is None:
          ret = None
      elif name == "":
          ret = postfix
      else:
          ret = "%s_%s" % (name, postfix)
      return ret
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import json
  import logging
  import math
  import six
  import numpy
  import paddle
  from paddle import nn
  from paddle.nn import functional
  from disco_diffusion_ernievil_base.vit_b_16x.ernievil2.transformers.file_utils import _fetch_from_remote, add_docstring
label_desc: Use image node_id 4 for calling a global function with example usage: append_name(name, postfix) and returns: ret