//    queue, immediately followed by another thread taking the next element in the queue. That
    //    second thread can then dispatch to the subscriber it took before the first thread does.
    //
    // All this makes me really wonder if there's any value in queueing here at all. A dispatcher
    // that simply loops through the subscribers and dispatches the event to each would actually

So:

```Python
q: Union[str, None] = Query(default=None)
```

...makes the parameter optional, with a default value of `None`, the same as:

```Python
q: Union[str, None] = None
```

And in Python 3.10 and above:

```Python
q: str | None = Query(default=None)
```

...makes the parameter optional, with a default value of `None`, the same as:

```Python

   * loader of that class from being garbage-collected even if there is a {@link SecurityManager}.
   * The {@link SecurityManager} environment makes such leaks more likely because when you create a
   * {@link URLClassLoader} with a {@link SecurityManager}, the creating code's {@link
   * java.security.AccessControlContext} is captured, and that references the creating code's {@link

Events
======

Events allow you to capture metrics on your application’s HTTP calls. Use events to monitor:

 * The size and frequency of the HTTP calls your application makes. If you’re making too many calls, or your calls are too large, you should know about it!
 * The performance of these calls on the underlying network. If the network’s performance isn’t sufficient, you need to either improve the network or use less of it.

### EventListener

    OkHttp used _get_ and _set_ prefixes sporadically which make the API
    inconsistent and awkward to explore.

 *  **OkHttpClient now implements the new `Call.Factory` interface.** This
    interface will make your code easier to test. When you test code that makes
    HTTP requests, you can use this interface to replace the real `OkHttpClient`
    with your own mocks or fakes.

			// since Linux 4.11.
			_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, unix.TCP_FASTOPEN_CONNECT, 1)

			// Enable TCP quick ACK, John Nagle says
			// "Set TCP_QUICKACK. If you find a case where that makes things worse, let me know."
			_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, unix.TCP_QUICKACK, 1)

			/// Enable keep-alive
			{
				_ = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1)

    than 63 characters between dots), and empty labels.
 *  New: Don't include the `Content-Length` header in multipart bodies. Servers must delimit
    OkHttp's request bodies using the boundary only. (This change makes OkHttp more consistent with
    browsers and other HTTP clients.)
 *  New: Drop the `tunnelProxy` argument in `MockWebServer.useHttps()`. This change only impacts
    the OkHttp 5.x API which uses the `mockwebserver3` package.

In the same way, you can use `finally` to make sure the exit steps are executed, no matter if there was an exception or not.

```Python hl_lines="3  5"
{!../../docs_src/dependencies/tutorial007.py!}
```

## Sub-dependencies with `yield`

You can have sub-dependencies and "trees" of sub-dependencies of any size and shape, and any or all of them can use `yield`.

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		{Name: "file.go", Data: []byte("hello"), Mode: 0644},
		{Name: "subfolder/another.go", Data: []byte("world"), Mode: 0644},
		// Notably missing here is the "subfolder" directory. This makes sure even
		// if we don't have a subfolder directory listed.
	}
	err := w.AddFS(writeTestsToFS(tests))
	if err != nil {
		t.Fatal(err)
	}
	if err := w.Close(); err != nil {
		t.Fatal(err)
	}