How to use the dynaconf.default_settings function in dynaconf

def _setup(self):
        """Initial setup, run once."""
        default_settings.reload()
        environment_variable = self._kwargs.get(
            "ENVVAR_FOR_DYNACONF", default_settings.ENVVAR_FOR_DYNACONF
        )
        settings_module = os.environ.get(environment_variable)
        self._wrapped = Settings(
            settings_module=settings_module, **self._kwargs
        )
        self.logger.debug("Lazy Settings _setup ...")

def color(_k):
        if _k in dir(default_settings):
            return "blue"
        return "green"

:param settings_path: the filepath
    :param settings_data: a dictionary with data
    :param merge: boolean if existing file should be merged with new data
    """
    settings_path = Path(settings_path)
    if settings_path.exists() and merge:  # pragma: no cover
        with io.open(
            str(settings_path), encoding=default_settings.ENCODING_FOR_DYNACONF
        ) as open_file:
            object_merge(toml.load(open_file), settings_data)

    with io.open(
        str(settings_path),
        "w",
        encoding=default_settings.ENCODING_FOR_DYNACONF,
    ) as open_file:
        toml.dump(settings_data, open_file)

def _setup(self):
        """Initial setup, run once."""
        default_settings.reload()
        environment_variable = self._kwargs.get(
            "ENVVAR_FOR_DYNACONF", default_settings.ENVVAR_FOR_DYNACONF
        )
        settings_module = os.environ.get(environment_variable)
        self._wrapped = Settings(
            settings_module=settings_module, **self._kwargs
        )
        self.logger.debug("Lazy Settings _setup ...")

def write(settings_path, settings_data, merge=True):
    """Write data to a settings file.

    :param settings_path: the filepath
    :param settings_data: a dictionary with data
    :param merge: boolean if existing file should be merged with new data
    """
    settings_path = Path(settings_path)
    if settings_path.exists() and merge:  # pragma: no cover
        with io.open(
            str(settings_path), encoding=default_settings.ENCODING_FOR_DYNACONF
        ) as open_file:
            object_merge(ConfigObj(open_file).dict(), settings_data)
    new = ConfigObj()
    new.update(settings_data)
    new.write(open(str(settings_path), "bw"))

if key.isupper()
    }

    all_keys = deduplicate(
        list(defaults.keys()) + list(default_settings_values.keys())
    )

    for key in all_keys:
        if not obj.exists(key):
            value = defaults.get(key, default_settings_values.get(key))
            obj.logger.debug("loading: %s:%s", key, value)
            obj.set(key, value)

    # start dotenv to get default env vars from there
    # check overrides in env vars
    default_settings.start_dotenv(obj)

    # Deal with cases where a custom ENV_SWITCHER_IS_PROVIDED
    # Example: Flask and Django Extensions
    env_switcher = defaults.get(
        "ENV_SWITCHER_FOR_DYNACONF", "ENV_FOR_DYNACONF"
    )

    for key in all_keys:
        if key not in default_settings_values.keys():
            continue

        env_value = obj.get_environ(
            env_switcher if key == "ENV_FOR_DYNACONF" else key,
            default="_not_found",
        )