val domainName = fromSource.readUtf8(domainNameLength.toLong())
          // Resolve HOSTNAME_THAT_ONLY_THE_PROXY_KNOWS to localhost.
          when {
            domainName.equals(HOSTNAME_THAT_ONLY_THE_PROXY_KNOWS, ignoreCase = true) -> {
              InetAddress.getByName("localhost")
            }
            else -> InetAddress.getByName(domainName)
          }
        }

```Python hl_lines="2"
# This is not asynchronous
def get_sequential_burgers(number: int):
    # Do some sequential stuff to create the burgers
    return burgers
```

With `async def`, Python knows that, inside that function, it has to be aware of `await` expressions, and that it can "pause" ⏸ the execution of that function and go do something else 🔀 before coming back.

!!! 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

In the examples above, you see that there's a tiny bit of **code duplication**.

## More motivation

Check this function, it already has type hints:

```Python hl_lines="1"
{!../../../docs_src/python_types/tutorial003.py!}
```

Because the editor knows the types of the variables, you don't only get completion, you also get error checks:

<img src="/img/python-types/image04.png">

Now you know that you have to fix it, convert `age` to a string with `str(age)`:

    }

    /**
     * Finds the parent symbol of the given [ResolveResult] by traversing back up the symbol hierarchy a [goBackSteps] steps,
     * or until the containing class or object symbol is found.
     *
     * Knows about the [ResolveResult.receiverClassReference] field and uses it in case it's not empty.
     */
    private fun KtAnalysisSession.findParentSymbol(resolveResult: ResolveResult, goBackSteps: Int, selectedFqName: FqName): KtSymbol? {

    locking. That's a potential security vulnerability, tracked as [CVE-2022-24329].
 *  Upgrade: [publicsuffix.org data][public_suffix]. This powers `HttpUrl.topPrivateDomain()`.
    It's also how OkHttp knows which domains can share cookies with one another.
 *  Upgrade: [Okio 3.2.0][okio_3_2_0].


## Version 4.10.0

_2022-06-12_

 *  Upgrade: [Kotlin 1.6.20][kotlin_1_6_20].
 *  Upgrade: [Okio 3.0.0][okio_3_0_0].