code: def op_func_chain(convert_func_list):
      """Run funcs one by one until func return is not None"""
      assert isinstance(convert_func_list, list)
  
      def _chain(op):
          for x in convert_func_list:
              ret = x(op)
              if ret is not None:
                  return ret
          return None
  
      return _chain
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  from functools import wraps
  import copy
  import numpy
  from caffe2.python import core, workspace
  from caffe2.proto import caffe2_pb2
label_desc: Use image node_id 3 for calling a global function with example usage: op_func_chain(convert_func_list) and returns: _chain, None, ret