code: def create_from_gbdt_json(cls, gbdt_json):
      retval = GBDTDecoder()
      retval.combination_method = 0
      retval.tree_list = list(
          GBDTDecoder.parse_turicreate_json(gbdt_json)
      )
      return retval
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  import turicreate
  import unittest
  import json
  import random
  import numpy
  import pytest
label_desc: Use image node_id 6 for calling the GBDTDecoder obj's underlying member method code with example usage: obj.create_from_gbdt_json(cls, gbdt_json) and returns: retval