How to use the stone.backends.swift_helpers.fmt_class function in stone

def _generate_client(self, api):
        self.emit_raw(base)
        self.emit('import Alamofire')
        self.emit()

        with self.block('open class {}'.format(self.args.class_name)):
            namespace_fields = []
            for namespace in api.namespaces.values():
                if namespace.routes:
                    namespace_fields.append((namespace.name,
                                            fmt_class(namespace.name)))
            for var, typ in namespace_fields:
                self.emit('/// Routes within the {} namespace. '
                          'See {}Routes for details.'.format(var, typ))
                self.emit('open var {}: {}Routes!'.format(var, typ))
            self.emit()

            with self.function_block('public init', args=self._func_args(
                    [('client', '{}'.format(self.args.transport_client_name))])):
                for var, typ in namespace_fields:
                    self.emit('self.{} = {}Routes(client: client)'.format(var, typ))

with self.class_block(data_type, protocols=protocols):
            for field in data_type.fields:
                fdoc = self.process_doc(field.doc,
                    self._docf) if field.doc else undocumented
                self.emit_wrapped_text(fdoc, prefix='/// ', width=120)
                self.emit('public let {}: {}'.format(
                    fmt_var(field.name),
                    fmt_type(field.data_type),
                ))
            self._generate_struct_init(namespace, data_type)

            decl = 'open var' if not data_type.parent_type else 'open override var'

            with self.block('{} description: String'.format(decl)):
                cls = fmt_class(data_type.name) + 'Serializer'
                self.emit('return "\\(SerializeUtil.prepareJSONForSerialization' +
                          '({}().serialize(self)))"'.format(cls))

        self._generate_struct_class_serializer(namespace, data_type)

def serializer_block(self, data_type):
        with self.class_block(fmt_class(data_type.name) + 'Serializer',
                              protocols=['JSONSerializer']):
            self.emit("public init() { }")
            yield

def _generate_struct_base_class_deserializer(self, namespace, data_type):
        args = []
        for field in data_type.all_fields:
            var = fmt_var(field.name)
            value = 'dict["{}"]'.format(field.name)
            self.emit('let {} = {}.deserialize({} ?? {})'.format(
                var,
                fmt_serial_obj(field.data_type),
                value,
                fmt_default_value(namespace, field) if field.has_default else '.null'
            ))

            args.append((var, var))
        self.emit('return {}({})'.format(
            fmt_class(data_type.name),
            self._func_args(args)
        ))

def serializer_func(self, data_type):
        with self.function_block('open func serialize',
                                 args=self._func_args([('_ value', fmt_class(data_type.name))]),
                                 return_type='JSON'):
            yield

def deserializer_func(self, data_type):
        with self.function_block('open func deserialize',
                                 args=self._func_args([('_ json', 'JSON')]),
                                 return_type=fmt_class(data_type.name)):
            yield

self.logger.info('Copying StoneValidators.swift to output folder')
        shutil.copy(os.path.join(rsrc_folder, 'StoneValidators.swift'),
                    self.target_folder_path)
        self.logger.info('Copying StoneSerializers.swift to output folder')
        shutil.copy(os.path.join(rsrc_folder, 'StoneSerializers.swift'),
                    self.target_folder_path)
        self.logger.info('Copying StoneBase.swift to output folder')
        shutil.copy(os.path.join(rsrc_folder, 'StoneBase.swift'),
                    self.target_folder_path)

        jazzy_cfg_path = os.path.join('../Format', 'jazzy.json')
        with open(jazzy_cfg_path) as jazzy_file:
            jazzy_cfg = json.load(jazzy_file)

        for namespace in api.namespaces.values():
            ns_class = fmt_class(namespace.name)
            with self.output_to_relative_path('{}.swift'.format(ns_class)):
                self._generate_base_namespace_module(api, namespace)
            jazzy_cfg['custom_categories'][1]['children'].append(ns_class)

            if namespace.routes:
                jazzy_cfg['custom_categories'][0]['children'].append(ns_class + 'Routes')

        with self.output_to_relative_path('../../../../.jazzy.json'):
            self.emit_raw(json.dumps(jazzy_cfg, indent=2) + '\n')

def generate(self, api):
        for namespace in api.namespaces.values():
            ns_class = fmt_class(namespace.name)
            if namespace.routes:
                with self.output_to_relative_path('{}Routes.swift'.format(ns_class)):
                    self._generate_routes(namespace)

        with self.output_to_relative_path('{}.swift'.format(self.args.module_name)):
            self._generate_client(api)

def _get_route_args(self, namespace, route):
        data_type = route.arg_data_type
        arg_type = fmt_type(data_type)
        if is_struct_type(data_type):
            arg_list = self._struct_init_args(data_type, namespace=namespace)

            doc_list = [(fmt_var(f.name), self.process_doc(f.doc, self._docf)
                if f.doc else undocumented) for f in data_type.fields if f.doc]
        elif is_union_type(data_type):
            arg_list = [(fmt_var(data_type.name), '{}.{}'.format(
                fmt_class(namespace.name), fmt_class(data_type.name)))]
            doc_list = [(fmt_var(data_type.name),
                self.process_doc(data_type.doc, self._docf)
                if data_type.doc else 'The {} union'.format(fmt_class(data_type.name)))]
        else:
            arg_list = [] if is_void_type(data_type) else [('request', arg_type)]
            doc_list = []
        return arg_list, doc_list