def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">
<summary>或者使用 <code>async def</code>...</summary>

如果你的代码里会出现 `async` / `await`，请使用 `async def`：

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():
    return {"Hello": "World"}

internal fun Int.toHexString(): String = Integer.toHexString(this)

@Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN", "NOTHING_TO_INLINE")
internal inline fun Any.wait() = (this as Object).wait()

@Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN", "NOTHING_TO_INLINE")
internal inline fun Any.notify() = (this as Object).notify()

@Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN", "NOTHING_TO_INLINE")

	var wg sync.WaitGroup
	for i := 0; i < 5; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			var buf [1]byte
			r.ReadAt(buf[:], int64(i))
		}(i)
	}
	wg.Wait()
}

func TestEmptyReaderConcurrent(t *testing.T) {
	// Test for the race detector, to verify a Read that doesn't yield any bytes
	// is okay to use from multiple goroutines. This was our historic behavior.

                this.inFlightLookups.add(name);
                return null;
            }
            while ( this.inFlightLookups.contains(name) ) {
                try {
                    this.inFlightLookups.wait();
                }
                catch ( InterruptedException e ) {
                    log.trace("Interrupted", e);
                }
            }
        }
        obj = getCachedAddress(name);

}

fun applyDefaultDependencies(model: CIBuildModel, buildType: BuildType, dependsOnQuickFeedbackLinux: Boolean) {
    if (dependsOnQuickFeedbackLinux) {
        // wait for quick feedback phase to finish successfully
        buildType.dependencies {
            dependsOn(RelativeId(stageTriggerId(model, StageName.QUICK_FEEDBACK_LINUX_ONLY)))
        }
    }

			if err != nil {
				return err
			}
			diskVersions[index] = resp.Sign
			dataDirs[index] = resp.OldDataDir
			return nil
		}, index)
	}

	// Wait for all renames to finish.
	errs := g.Wait()

	err := reduceWriteQuorumErrs(ctx, errs, objectOpIgnoredErrs, writeQuorum)
	if err != nil {
		dg := errgroup.WithNErrs(len(disks))
		for index, nerr := range errs {

      assertEquals(cancelMode == INTERRUPT, Thread.interrupted())
    }
    responseBody.close()
    assertEquals(if (connectionType == H2) 1 else 0, client.connectionPool.connectionCount())

    cancelLatch.await()

    val events = listener.eventSequence.filter { isConnectionEvent(it) }.map { it.name }
    listener.clearAllEvents()

    assertThat(events).startsWith("CallStart", "ConnectStart", "ConnectEnd", "ConnectionAcquired")

{!../../docs_src/app_testing/tutorial001.py!}
```

/// tip | "Dica"

Observe que as funções de teste são `def` normais, não `async def`.

E as chamadas para o cliente também são chamadas normais, não usando `await`.

Isso permite que você use `pytest` diretamente sem complicações.

///

/// note | "Detalhes técnicos"

Você também pode usar `from starlette.testclient import TestClient`.

    // observe a size of 1
    long initialSize = cache.size();
    assertTrue(initialSize == 1 || initialSize == 2);

    // wait up to 5s
    byte[] filler = new byte[1024];
    for (int i = 0; i < 500; i++) {
      System.gc();

      CacheTesting.drainReferenceQueues(cache);
      if (cache.size() == 1) {
        break;
      }

				// Number of probes.
				// ~ cat /proc/sys/net/ipv4/tcp_keepalive_probes (defaults to 9, we reduce it to 5)
				_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_KEEPCNT, 5)

				// Wait time after successful probe in seconds.
				// ~ cat /proc/sys/net/ipv4/tcp_keepalive_intvl (defaults to 75 secs, we reduce it to 15 secs)
				_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, 15)
			}