### Diğer yardımcı fonksiyonlar

Doğrudan çağırdığınız diğer herhangi bir yardımcı fonksiyonu, normal "def" veya "async def" ile tanimlayabilirsiniz. FastAPI onu çağırma şeklinizi etkilemez.

## The normal **FastAPI** app

Let's first see how the normal API app would look like before adding the callback.

It will have a *path operation* that will receive an `Invoice` body, and a query parameter `callback_url` that will contain the URL for the callback.

This part is pretty normal, most of the code is probably already familiar to you:

        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="17"
    {!> ../../../docs_src/dependencies/tutorial006.py!}
    ```

These dependencies will be executed/solved the same way as normal dependencies. But their value (if they return any) won't be passed to your *path operation function*.

!!! tip
    Some editors check for unused function parameters, and show them as errors.

import assertk.assertions.isEqualTo
import assertk.assertions.isNotNull
import assertk.assertions.isNull
import assertk.assertions.matches
import java.net.http.HttpClient
import java.net.http.HttpClient.Redirect.NORMAL
import java.net.http.HttpRequest
import java.net.http.HttpResponse.BodyHandlers
import mockwebserver3.MockResponse
import mockwebserver3.MockWebServer
import okhttp3.testing.PlatformRule

// current scale target (e.g. CPU or memory).  The values will be averaged
// together before being compared to the target.  Such metrics are built in to
// Kubernetes, and have special scaling options on top of those available to
// normal per-pod metrics using the "pods" source.  Only one "target" type
// should be set.
message ContainerResourceMetricSource {
  // name is the name of the resource in question.
  optional string name = 1;

// current scale target (e.g. CPU or memory).  The values will be averaged
// together before being compared to the target.  Such metrics are built in to
// Kubernetes, and have special scaling options on top of those available to
// normal per-pod metrics using the "pods" source.  Only one "target" type
// should be set.
message ContainerResourceMetricSource {
  // name is the name of the resource in question.
  optional string name = 1;

      log.put("normal task running")
      return@schedule -1L
    }

    queue.idleLatch().await(500, TimeUnit.MILLISECONDS)

    assertThat(log.take()).isEqualTo("failing task running")
    assertThat(log.take()).isEqualTo("uncaught exception: java.lang.RuntimeException: boom!")
    assertThat(log.take()).isEqualTo("normal task running")
    assertThat(log).isEmpty()
  }

It is just a standard function that can receive parameters.

It can be an `async def` or normal `def` function, **FastAPI** will know how to handle it correctly.

In this case, the task function will write to a file (simulating sending an email).

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

```Python hl_lines="6-9"
{!../../../docs_src/background_tasks/tutorial001.py!}
```

[2020-01-01 00:00:00] << 0x00000003   288 DATA
[2020-01-01 00:00:00] << 0x00000003     0 DATA          END_STREAM
[2020-01-01 00:00:00] << 0x00000000     8 GOAWAY
[2020-01-01 00:00:05] << 0x00000000     8 GOAWAY
```

### Task Runner Logging 

This logs task enqueues, starts, and finishes.

```
[2020-01-01 00:00:00] Q10000 scheduled after   0 µs: OkHttp ConnectionPool

 * after the garbage collector reclaims the referent. This is a simpler alternative to using a
 * {@link ReferenceQueue}.
 *
 * <p>Unlike a normal phantom reference, this reference will be cleared automatically.
 *
 * @author Bob Lee
 * @since 2.0
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault