{!../../docs_src/bigger_applications/app/routers/items.py!}
```

#### How relative imports work

/// tip

If you know perfectly how imports work, continue to the next section below.

///

A single dot `.`, like in:

```Python
from .dependencies import get_token_header
```

would mean:

 * of the access check algorithm used by Windows is required. The following
 * is a basic description of the algorithm. For a more complete description
 * we recommend reading the section on Access Control in Keith Brown's
 * "The .NET Developer's Guide to Windows Security" (which is also
 * available online).
 * <p>
 * Direct ACEs are evaluated first in order. The SID of the user performing

 * on what responses can be stored, and which requests can be satisfied by those stored responses.
 *
 * See [RFC 7234, 5.2](https://tools.ietf.org/html/rfc7234#section-5.2).
 */
class CacheControl internal constructor(
  /**
   * In a response, this field's name "no-cache" is misleading. It doesn't prevent us from caching

 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.escape;

import static com.google.common.base.Preconditions.checkNotNull;
import static java.lang.Math.min;

import com.google.common.annotations.GwtCompatible;
import java.util.Map;
import javax.annotation.CheckForNull;

{!> ../../docs_src/websockets/tutorial002.py!}
```

////

/// info

由于这是一个 WebSocket，抛出 `HTTPException` 并不是很合理，而是抛出 `WebSocketException`。

您可以使用<a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">规范中定义的有效代码</a>。

///

### 尝试带有依赖项的 WebSockets

如果您的文件名为 `main.py`，请使用以下命令运行应用程序：

```console
$ uvicorn main:app --reload

//
//   - Optional: Set server preferences for Backup & Replication parallel sessions, batch size of deletes, and block sizes (before
//     compression). This is an optional area; by default, there should be no <SystemRecommendations> section in the
//     system.xml. Vendors can work with Veeam Product Management and the Alliances team on getting approval to integrate

  }

  // From RFC 3720, Section 12.1, the polynomial generator is 0x11EDC6F41.
  // We calculate the constant below by:
  //   1. Omitting the most significant bit (because it's always 1). => 0x1EDC6F41
  //   2. Flipping the bits of the constant so we can process a byte at a time. => 0x82F63B78
  private static final int CRC32C_GENERATOR = 0x1EDC6F41; // 0x11EDC6F41

 * the License.
 */

package com.google.common.primitives;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.GwtCompatible;

 * the License.
 */

package com.google.common.primitives;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.GwtCompatible;

Sie können einen „Closing“-Code verwenden, aus den <a href="https://tools.ietf.org/html/rfc6455#section-7.4.1" class="external-link" target="_blank">gültigen Codes, die in der Spezifikation definiert sind</a>.

///

### WebSockets mit Abhängigkeiten ausprobieren