https://airflow.apache.org/docs/apache-airflow/stable/configurations-ref.html#store-dag-code

![Captura de pantalla 2021-05-26 a las 17 47 56](https://user-images.githubusercontent.com/11339132/119691160-a2049a00-be4a-11eb-8f55-0ad2c6117620.png)

The Default is True or None?
tests/core/test_configuration.py
assert conf.get("core", "percent") == "with%inside"
        assert conf.get("core", "PERCENT") == "with%inside"
        assert conf.get("CORE", "PERCENT") == "with%inside"
    def test_config_as_dict(self):
        """Test that getting config as dict works even if
        environment has non-legal env vars"""
        with unittest.mock.patch.dict('os.environ'):
            os.environ['AIRFLOW__VAR__broken'] = "not_ok"
            asdict = conf.as_dict(raw=True, display_sensitive=True)
        assert asdict.get('VAR') is None
        assert asdict['testsection']['testkey'] == 'testvalue'
    def test_env_var_config(self):
        opt = conf.get('testsection', 'testkey')
        assert opt == 'testvalue'
        opt = conf.get('testsection', 'testpercent')
        assert opt == 'with%percent'
        assert conf.has_option('testsection', 'testkey')
        with unittest.mock.patch.dict(
            'os.environ', AIRFLOW__KUBERNETES_ENVIRONMENT_VARIABLES__AIRFLOW__TESTSECTION__TESTKEY='nested'
        ):
            opt = conf.get('kubernetes_environment_variables', 'AIRFLOW__TESTSECTION__TESTKEY')
            assert opt == 'nested'
    @mock.patch.dict(
        'os.environ', AIRFLOW__KUBERNETES_ENVIRONMENT_VARIABLES__AIRFLOW__TESTSECTION__TESTKEY='nested'
    )
    @conf_vars({("core", "percent"): "with%%inside"})
    def test_conf_as_dict(self):