Beginnen wir mit einem Beispiel und sehen es uns dann im Detail an.

Wir erstellen eine asynchrone Funktion `lifespan()` mit `yield` wie folgt:

```Python hl_lines="16  19"
{!../../docs_src/events/tutorial003.py!}
```

                "HTTPValidationError": {
                    "title": "HTTPValidationError",
                    "type": "object",
                    "properties": {
                        "detail": {
                            "title": "Detail",
                            "type": "array",
                            "items": {"$ref": "#/components/schemas/ValidationError"},
                        }
                    },

    long rem = dividend - quotient * divisor;
    return rem - (compare(rem, divisor) >= 0 ? divisor : 0);
  }

  /**
   * Returns the unsigned {@code long} value represented by the given decimal string.
   *
   * <p><b>Java 8+ users:</b> use {@link Long#parseUnsignedLong(String)} instead.
   *
   * @throws NumberFormatException if the string does not contain a valid unsigned {@code long}
   *     value

    // our connection coalescing requirements are met. See also:
    // https://hpbn.co/optimizing-application-delivery/#eliminate-domain-sharding
    // https://daniel.haxx.se/blog/2016/08/18/http2-connection-coalescing/

    // 1. This connection must be HTTP/2.
    if (http2Connection == null) return false

    // 2. The routes must share an IP address.

 * has not actually been put in the {@code BloomFilter}.
 *
 * <p>Bloom filters are serializable. They also support a more compact serial representation via the
 * {@link #writeTo} and {@link #readFrom} methods. Both serialized forms will continue to be
 * supported by future versions of this library. However, serial forms generated by newer versions
 * of the code may not be readable by older versions of the code (e.g., a serialized Bloom filter

//
// Note that the GNU manual says that numeric values should be encoded in octal
// format. However, the GNU tar utility itself outputs these values in decimal.
// As such, this library treats values as being encoded in decimal.
func readGNUSparseMap1x0(r io.Reader) (sparseDatas, error) {
	var (
		cntNewline int64
		buf        bytes.Buffer
		blk        block
	)

    }
    // Waiting 68 years should be enough for any program.
    return super.get(
        min(timeoutNanos, OverflowAvoidingLockSupport.MAX_NANOSECONDS_THRESHOLD), NANOSECONDS);
  }

  /** Internal implementation detail used to invoke the listeners. */
  @Override
  protected void done() {
    executionList.execute();
  }

## Get started

In this document we will explain in detail on how to configure admin users.

### 1. Prerequisites

- Install mc - [MinIO Client Quickstart Guide](https://min.io/docs/minio/linux/reference/minio-mc.html#quickstart)

3.  Guava has one dependency that is needed for linkage at runtime:
    `com.google.guava:failureaccess:1.0.2`. It also has
    [some annotation-only dependencies][guava-deps], which we discuss in more
    detail at that link.

4.  Serialized forms of ALL objects are subject to change unless noted
    otherwise. Do not persist these and assume they can be read by a future
    version of the library.

```

这里的查询参数 `needy` 是类型为 `str` 的必选查询参数。

在浏览器中打开如下 URL：

```
http://127.0.0.1:8000/items/foo-item
```

……因为路径中没有必选参数 `needy`，返回的响应中会显示如下错误信息：

```JSON
{
    "detail": [
        {
            "loc": [
                "query",
                "needy"
            ],
            "msg": "field required",
            "type": "value_error.missing"
        }
    ]
}