// SafeClose safely closes any channel of any type
func SafeClose[T any](c chan<- T) {
	if c != nil {
		close(c)
		return
	}
	// Print stack to check who is sending `c` as `nil`
	// without crashing the server.
	debug.PrintStack()

    copy the object code is a network server, the Corresponding Source
    may be on a different server (operated by you or a third party)
    that supports equivalent copying facilities, provided you maintain
    clear directions next to the object code saying where to find the
    Corresponding Source.  Regardless of what server hosts the
    Corresponding Source, you remain obligated to ensure that it is

     * place. For example at the time of this writing the readXxxWireFormat
     * for requests and the writeXxxWireFormat for responses are not implemented
     * and simply return 0. These would need to be completed for a server
     * implementation.
     */

    static final byte SMB_COM_CREATE_DIRECTORY   = (byte)0x00;
    static final byte SMB_COM_DELETE_DIRECTORY   = (byte)0x01;

    --hash=sha256:a6df30f272c08bf8be66e0775fad862005d950a6b8449b94f7c788731d70ecd7
    # via -r ci/official/requirements_updater/requirements.in
tensorboard-data-server==0.7.2 \
    --hash=sha256:7e0610d205889588983836ec05dc098e80f97b7e7bbff7e994ebb78f578d0ddb \
    --hash=sha256:9fe5d24221b29625dbc7328b0436ca7fc1c23de4acf4d272f1180856e32f9f60 \

```

////

As in this case (without using `Annotated`) we have to replace the default value `None` in the function with `Query()`, we now need to set the default value with the parameter `Query(default=None)`, it serves the same purpose of defining that default value (at least for FastAPI).

So:

```Python
q: Union[str, None] = Query(default=None)
```

通过以下命令运行服务器：

<div class="termy">

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

INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [28720]
INFO:     Started server process [28722]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
```

</div>

<details markdown="1">
<summary>关于 <code>uvicorn main:app --reload</code> 命令......</summary>

      <url>https://oss.sonatype.org/service/local/staging/deploy/maven2/</url>
    </repository>
    <site>
      <id>guava-site</id>
      <name>Guava Documentation Site</name>
      <url>scp://dummy.server/dontinstall/usestaging</url>
    </site>
  </distributionManagement>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>com.google.code.findbugs</groupId>

      <url>https://oss.sonatype.org/service/local/staging/deploy/maven2/</url>
    </repository>
    <site>
      <id>guava-site</id>
      <name>Guava Documentation Site</name>
      <url>scp://dummy.server/dontinstall/usestaging</url>
    </site>
  </distributionManagement>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>com.google.code.findbugs</groupId>

                    <mxGeometry x="450" y="-50" width="820" height="970" as="geometry"/>
                </mxCell>
                <mxCell id="3" value="&lt;font face=&quot;Roboto&quot;&gt;&lt;span style=&quot;font-size: 24px&quot;&gt;Server(s)&lt;/span&gt;&lt;/font&gt;" style="text;html=1;strokeColor=none;fillColor=none;align=center;verticalAlign=middle;whiteSpace=wrap;rounded=0;strokeWidth=3;fontFamily=Roboto Mono, mono;FType=g;" parent="1" vertex="1">

var ntpServer = env.Get(ntpServerEnv, "")

// UTCNowNTP - is similar in functionality to UTCNow()
// but only used when we do not wish to rely on system
// time.
func UTCNowNTP() (time.Time, error) {
	// ntp server is disabled
	if ntpServer == "" {
		return time.Now().UTC(), nil
	}
	return ntp.Time(ntpServer)
}

// Retention - bucket level retention configuration.
type Retention struct {
	Mode        RetMode