* entries may be counted in {@link Cache#size}, but will never be visible to read or write
 * operations.
 *
 * <p>Certain cache configurations will result in the accrual of periodic maintenance tasks which
 * will be performed during write operations, or during occasional read operations in the absence of
 * writes. The {@link Cache#cleanUp} method of the returned cache will also perform maintenance, but

    /**
     * This method will delete the file or directory specified by this
     * <code>SmbResource</code>. If the target is a directory, the contents of
     * the directory will be deleted as well. If a file within the directory or
     * it's sub-directories is marked read-only, the read-only status will
     * be removed and the file will be deleted.
     *

Also, before that, in previous versions, the `request` object was passed as part of the key-value pairs in the context for Jinja2.

///

/// tip

By declaring `response_class=HTMLResponse` the docs UI will be able to know that the response will be HTML.

///

/// note | Technical Details

You could also use `from starlette.templating import Jinja2Templates`.

{* ../../docs_src/body_nested_models/tutorial003_py310.py hl[12] *}

With this, even if you receive a request with duplicate data, it will be converted to a set of unique items.

And whenever you output that data, even if the source had duplicates, it will be output as a set of unique items.

And it will be annotated / documented accordingly too.

## Nested Models { #nested-models }

Each attribute of a Pydantic model has a type.

     * protocols. The http/1.1 transport will never be dropped.
     *
     * If multiple protocols are specified, [ALPN][alpn] will be used to negotiate a transport.
     * Protocol negotiation is only attempted for HTTPS URLs.
     *
     * [Protocol.HTTP_1_0] is not supported in this set. Requests are initiated with `HTTP/1.1`. If
     * the server responds with `HTTP/1.0`, that will be exposed by [Response.protocol].
     *

   * returned from {@link #asMapOfRanges} will be different if there were existing entries which
   * connect to the given range and value.
   *
   * <p>Even if the input range is empty, if it is connected on both sides by ranges mapped to the
   * same value those two ranges will be coalesced.
   *

* Then it returns the **response**.

/// note | Technical Details

If you have dependencies with `yield`, the exit code will run *after* the middleware.

If there were any background tasks (covered in the [Background Tasks](background-tasks.md){.internal-link target=_blank} section, you will see it later), they will run *after* all the middleware.

///

## Create a middleware { #create-a-middleware }

## Check it { #check-it }

Now, every request under the path `/v1/` will be handled by the Flask application.

And the rest will be handled by **FastAPI**.

If you run it and go to <a href="http://localhost:8000/v1/" class="external-link" target="_blank">http://localhost:8000/v1/</a> you will see the response from Flask:

```txt
Hello, World from Flask!
```

```

The parameter values in your function will be:

* `skip=20`: because you set it in the URL
* `limit=10`: because that was the default value

## Optional parameters { #optional-parameters }

The same way, you can declare optional query parameters, by setting their default to `None`:

{* ../../docs_src/query_params/tutorial002_py310.py hl[7] *}

In this case, the function parameter `q` will be optional, and will be `None` by default.

   * and column pair, they will be combined with the specified merging function in encounter order.
   *
   * <p>The returned {@code Collector} will throw a {@code NullPointerException} at collection time
   * if the row, column, value, or merging functions return null on any input.
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */
  @IgnoreJRERequirement // Users will use this only if they're already using streams.