How to use the mkdocs.config.base.ValidationError function in mkdocs

def run_validation(self, value):
        if value == '':
            return value

        try:
            parsed_url = urlparse(value)
        except (AttributeError, TypeError):
            raise ValidationError("Unable to parse the URL.")

        if parsed_url.scheme:
            return value

        raise ValidationError(
            "The URL isn't valid, it should include the http:// (scheme)")

def run_validation(self, value):
        try:
            host, port = value.rsplit(':', 1)
        except Exception:
            raise ValidationError("Must be a string of format 'IP:PORT'")

        try:
            port = int(port)
        except Exception:
            raise ValidationError("'{}' is not a valid port".format(port))

        class Address(namedtuple('Address', 'host port')):
            def __str__(self):
                return '{}:{}'.format(self.host, self.port)

        return Address(host, port)

def _load_theme_config(self, name):
        """ Recursively load theme and any parent themes. """

        theme_dir = utils.get_theme_dir(name)
        self.dirs.append(theme_dir)

        try:
            file_path = os.path.join(theme_dir, 'mkdocs_theme.yml')
            with open(file_path, 'rb') as f:
                theme_config = utils.yaml_load(f)
                if theme_config is None:
                    theme_config = {}
        except OSError as e:
            log.debug(e)
            raise ValidationError(
                "The theme '{}' does not appear to have a configuration file. "
                "Please upgrade to a current version of the theme.".format(name)
            )

        log.debug("Loaded theme configuration for '%s' from '%s': %s", name, file_path, theme_config)

        parent_theme = theme_config.pop('extends', None)
        if parent_theme:
            themes = utils.get_theme_names()
            if parent_theme not in themes:
                raise ValidationError(
                    "The theme '{}' inherits from '{}', which does not appear to be installed. "
                    "The available installed themes are: {}".format(name, parent_theme, ', '.join(themes))
                )
            self._load_theme_config(parent_theme)

Plugin = self.installed_plugins[name].load()

        if not issubclass(Plugin, plugins.BasePlugin):
            raise ValidationError('{}.{} must be a subclass of {}.{}'.format(
                Plugin.__module__, Plugin.__name__, plugins.BasePlugin.__module__,
                plugins.BasePlugin.__name__))

        plugin = Plugin()
        errors, warnings = plugin.load_config(config, self.config_file_path)
        self.warnings.extend(warnings)
        errors_message = '\n'.join(
            "Plugin value: '{}'. Error: {}".format(x, y)
            for x, y in errors
        )
        if errors_message:
            raise ValidationError(errors_message)
        return plugin

def load_plugin(self, name, config):
        if name not in self.installed_plugins:
            raise ValidationError('The "{}" plugin is not installed'.format(name))

        Plugin = self.installed_plugins[name].load()

        if not issubclass(Plugin, plugins.BasePlugin):
            raise ValidationError('{}.{} must be a subclass of {}.{}'.format(
                Plugin.__module__, Plugin.__name__, plugins.BasePlugin.__module__,
                plugins.BasePlugin.__name__))

        plugin = Plugin()
        errors, warnings = plugin.load_config(config, self.config_file_path)
        self.warnings.extend(warnings)
        errors_message = '\n'.join(
            "Plugin value: '{}'. Error: {}".format(x, y)
            for x, y in errors
        )
        if errors_message:
            raise ValidationError(errors_message)
        return plugin

def run_validation(self, value):
        raise ValidationError('For internal use only.')

def run_validation(self, value):

        if not isinstance(value, self._type):
            msg = ("Expected type: {} but received: {}"
                   .format(self._type, type(value)))
        elif self.length is not None and len(value) != self.length:
            msg = ("Expected type: {0} with length {2} but received: {1} with "
                   "length {3}").format(self._type, value, self.length,
                                        len(value))
        else:
            return value

        raise ValidationError(msg)

def run_validation(self, value):
        if value is None:
            if self.required:
                raise ValidationError("Required configuration not provided.")
            else:
                return ()

        if not isinstance(value, Sequence):
            raise ValidationError('Expected a sequence of mappings, but a %s '
                                  'was given.' % type(value))
        result = []
        for item in value:
            result.append(self.item_config.validate(item))
        return result

def post_validation(self, config, key_name):
        if config.config_file_path is None:
            return

        # Validate that the dir is not the parent dir of the config file.
        if os.path.dirname(config.config_file_path) == config[key_name]:
            raise ValidationError(
                ("The '{}' should not be the parent directory of the config "
                 "file. Use a child directory instead so that the config file "
                 "is a sibling of the config file.").format(key_name))

def run_validation(self, value):
        if not isinstance(value, (list, tuple)):
            raise ValidationError('Invalid Markdown Extensions configuration')
        extensions = []
        for item in value:
            if isinstance(item, dict):
                if len(item) > 1:
                    raise ValidationError('Invalid Markdown Extensions configuration')
                ext, cfg = item.popitem()
                extensions.append(ext)
                if cfg is None:
                    continue
                if not isinstance(cfg, dict):
                    raise ValidationError('Invalid config options for Markdown '
                                          "Extension '{}'.".format(ext))
                self.configdata[ext] = cfg
            elif isinstance(item, str):
                extensions.append(item)
            else:
                raise ValidationError('Invalid Markdown Extensions configuration')

        extensions = utils.reduce_list(self.builtins + extensions)

        # Confirm that Markdown considers extensions to be valid