code: def test_use_default_value(self):
      config_json = json.loads(
          """
              {}
          """
      )
      config = config_from_json(Model1, config_json)
      self.assertEqual(config.foo, 1)
  
imports: import json
  import unittest
  from typing import List, Tuple, Union
  from pytext.config.component import Component, ComponentType
  from pytext.config.pytext_config import ConfigBase
  from pytext.config.serialize import config_from_json, config_to_json, ConfigParseError, MissingValueError, UnionTypeError
label_desc: Use image node_id 1 for calling the PytextConfigTest obj's underlying member method code with example usage: obj.test_use_default_value() without return types