code: def test_is_valid_json(self):
      assert functions.is_valid_json({"x": ["i am serializable", 0.1]})
      assert not functions.is_valid_json(
          {"x": RandomForestClassifier()}
      )
  
imports: from __future__ import absolute_import, print_function, division, unicode_literals
  import unittest
  import os
  import numpy
  from xcessiv import functions, exceptions
  from sklearn.datasets import load_digits
  from sklearn.ensemble import RandomForestClassifier
  from sklearn.decomposition import PCA
  from sklearn.pipeline import Pipeline
  import pickle
label_desc: Use image node_id 1 for calling the TestIsValidJSON obj's underlying member method code with example usage: obj.test_is_valid_json() without return types