### Return values { #return-values }

And they can return values or not, the values won't be used.

So, you can reuse a normal dependency (that returns a value) you already use somewhere else, and even though the value won't be used, the dependency will be executed:

{* ../../docs_src/dependencies/tutorial006_an_py39.py hl[11,16] *}

You also define in some way at which **moments** your app will send those requests or events.

And **your users** define in some way (for example in a web dashboard somewhere) the **URL** where your app should send those requests.

All the **logic** about how to register the URLs for webhooks and the code to actually send those requests is up to you. You write it however you want to in **your own code**.

        * And if the token is stolen, the risk is less. It is not like a permanent key that will work forever (in most of the cases).
* The frontend stores that token temporarily somewhere.
* The user clicks in the frontend to go to another section of the frontend web app.
* The frontend needs to fetch some more data from the API.
    * But it needs authentication for that specific endpoint.

			sep:      slashSeparator,
			want:     true,
		},
		{
			testName: "deeper-file",
			entry:    "src/dir/somewhere.ext",
			dir:      "src/",
			sep:      slashSeparator,
			want:     false,
		},
		{
			testName: "deeper-dir",
			entry:    "src/dir/somewhere/",
			dir:      "src/",
			sep:      slashSeparator,
			want:     false,
		},
		{
			testName: "root-dir",

common_parameters --> read_users
```

This way you write shared code once and **FastAPI** takes care of calling it for your *path operations*.

/// check

Notice that you don't have to create a special class and pass it somewhere to **FastAPI** to "register" it or anything similar.

You just pass it to `Depends` and **FastAPI** knows how to do the rest.

///

## Share `Annotated` dependencies { #share-annotated-dependencies }

## Asynchronous Code { #asynchronous-code }

Asynchronous code just means that the language 💬 has a way to tell the computer / program 🤖 that at some point in the code, it 🤖 will have to wait for *something else* to finish somewhere else. Let's say that *something else* is called "slow-file" 📝.

So, during that time, the computer can go and do some other work, while "slow-file" 📝 finishes.

	objectName := "test-object"
	opts := ObjectOptions{}
	// byte data for PutObject.
	bytesData := generateBytesData(6 * humanize.KiByte)

	copySourceHeader := map[string]string{"X-Amz-Copy-Source": "somewhere"}
	invalidMD5Header := map[string]string{"Content-Md5": "42"}
	invalidStorageClassHeader := map[string]string{xhttp.AmzStorageClass: "INVALID"}