code: def get_json_trees(self):
      dict_trees = map(lambda x: x.to_dict(), self.tree_list)
      js_trees = map(lambda x: json.dumps(x), dict_trees)
      # ret_json = json.dumps(js_trees)
      return js_trees
  
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 7 for calling the GBDTDecoder obj's underlying member method code with example usage: obj.get_json_trees() and returns: js_trees