How to use the starlette.middleware.Middleware function in starlette

def test_app_middleware_argument():
    def homepage(request):
        return PlainTextResponse("Homepage")

    app = Starlette(
        routes=[Route("/", homepage)], middleware=[Middleware(CustomMiddleware)]
    )

    client = TestClient(app)
    response = client.get("/")
    assert response.headers["Custom-Header"] == "Example"

def test_middleware_repr():
    middleware = Middleware(CustomMiddleware)
    assert repr(middleware) == "Middleware(CustomMiddleware)"

async def test_duplicate_caching() -> None:
    cache = Cache("locmem://default")
    special_cache = Cache("locmem://special")

    class DuplicateCache(HTTPEndpoint):
        pass

    app = Starlette(
        routes=[
            Route(
                "/duplicate_cache", CacheMiddleware(DuplicateCache, cache=special_cache)
            )
        ],
        middleware=[Middleware(CacheMiddleware, cache=cache)],
    )

    client = httpx.AsyncClient(app=app, base_url="http://testserver")

    async with cache, special_cache, client:
        with pytest.raises(DuplicateCaching):
            await client.get("/duplicate_cache")

for key, value in self.exception_handlers.items():
            if key in (500, Exception):
                error_handler = value
            else:
                exception_handlers[key] = value

        middlewares = []

        if config.ALLOWED_HOSTS != ["*"]:
            middlewares.append(
                Middleware(TrustedHostMiddleware, allowed_hosts=config.ALLOWED_HOSTS)
            )

        middlewares.append(
            Middleware(ServerErrorMiddleware, handler=error_handler, debug=config.DEBUG)
        )

        if (
            config.CORS_ALLOW_ORIGIN_REGEX is not None
            or len(config.CORS_ALLOW_ORIGINS) > 0
        ):
            middlewares.append(
                Middleware(
                    CORSMiddleware,
                    allow_origins=config.CORS_ALLOW_ORIGINS,
                    allow_methods=config.CORS_ALLOW_METHODS,
                    allow_headers=config.CORS_ALLOW_HEADERS,
                    allow_credentials=config.CORS_ALLOW_CREDENTIALS,
                    allow_origin_regex=config.CORS_ALLOW_ORIGIN_REGEX,
                    expose_headers=config.CORS_EXPOSE_HEADERS,
                    max_age=config.CORS_MAX_AGE,

def build_app(self) -> ASGIApp:
        config = self.config
        error_handler = None
        exception_handlers = {}

        for key, value in self.exception_handlers.items():
            if key in (500, Exception):
                error_handler = value
            else:
                exception_handlers[key] = value

        middlewares = []

        if config.ALLOWED_HOSTS != ["*"]:
            middlewares.append(
                Middleware(TrustedHostMiddleware, allowed_hosts=config.ALLOWED_HOSTS)
            )

        middlewares.append(
            Middleware(ServerErrorMiddleware, handler=error_handler, debug=config.DEBUG)
        )

        if (
            config.CORS_ALLOW_ORIGIN_REGEX is not None
            or len(config.CORS_ALLOW_ORIGINS) > 0
        ):
            middlewares.append(
                Middleware(
                    CORSMiddleware,
                    allow_origins=config.CORS_ALLOW_ORIGINS,
                    allow_methods=config.CORS_ALLOW_METHODS,
                    allow_headers=config.CORS_ALLOW_HEADERS,

def build_middleware_stack(self) -> ASGIApp:
        debug = self.debug
        error_handler = None
        exception_handlers = {}

        for key, value in self.exception_handlers.items():
            if key in (500, Exception):
                error_handler = value
            else:
                exception_handlers[key] = value

        middleware = (
            [Middleware(ServerErrorMiddleware, handler=error_handler, debug=debug,)]
            + self.user_middleware
            + [
                Middleware(
                    ExceptionMiddleware, handlers=exception_handlers, debug=debug,
                )
            ]
        )

        app = self.router
        for cls, options in reversed(middleware):
            app = cls(app=app, **options)
        return app

def build_middleware_stack(self) -> ASGIApp:
        debug = self.debug
        error_handler = None
        exception_handlers = {}

        for key, value in self.exception_handlers.items():
            if key in (500, Exception):
                error_handler = value
            else:
                exception_handlers[key] = value

        middleware = (
            [Middleware(ServerErrorMiddleware, handler=error_handler, debug=debug,)]
            + self.user_middleware
            + [
                Middleware(
                    ExceptionMiddleware, handlers=exception_handlers, debug=debug,
                )
            ]
        )

        app = self.router
        for cls, options in reversed(middleware):
            app = cls(app=app, **options)
        return app

middlewares.append(
                Middleware(
                    CORSMiddleware,
                    allow_origins=config.CORS_ALLOW_ORIGINS,
                    allow_methods=config.CORS_ALLOW_METHODS,
                    allow_headers=config.CORS_ALLOW_HEADERS,
                    allow_credentials=config.CORS_ALLOW_CREDENTIALS,
                    allow_origin_regex=config.CORS_ALLOW_ORIGIN_REGEX,
                    expose_headers=config.CORS_EXPOSE_HEADERS,
                    max_age=config.CORS_MAX_AGE,
                )
            )

        middlewares += self.user_middlewares

        middlewares.append(Middleware(ExceptionMiddleware, handlers=exception_handlers))

        app = self.app

        for cls, options in reversed(middlewares):
            app = cls(app=app, **options)
        return app