* implement subtleties of the API improperly.
 *
 * <p><b>Custom implementation</b>: Avoid implementing {@code ListenableFuture} from scratch. If you
 * can't get by with the standard implementations, prefer to derive a new {@code Future} instance
 * with the methods in {@link Futures} or, if necessary, to extend {@link AbstractFuture}.
 *

This is not a limitation of **FastAPI**, it's part of the HTTP protocol.

///

## Optional File Upload { #optional-file-upload }

You can make a file optional by using standard type annotations and setting a default value of `None`:

{* ../../docs_src/request_files/tutorial001_02_an_py310.py hl[9,17] *}

## `UploadFile` with Additional Metadata { #uploadfile-with-additional-metadata }

 * This class manages the rules defined in a robots.txt file, including user agent directives,
 * allowed/disallowed paths, crawl delays, and sitemap URLs.
 *
 * <p>The robots.txt protocol is implemented according to the standard specification,
 * supporting pattern matching for user agents, path-based access control, and crawl delay settings.</p>
 *
 * <p>Key features:</p>
 * <ul>

        ),
      )

    call.execute().use { response ->
      assertThat(response.body.string()).isEqualTo("abc")
    }

    val expectedEvents = mutableListOf<String>()
    // Start out with standard events...
    expectedEvents += "CallStart"
    expectedEvents += "ProxySelectStart"
    expectedEvents += "ProxySelectEnd"
    expectedEvents += "DnsStart"
    expectedEvents += "DnsEnd"

                    return new StandardImplForwardingNavigableMap<>(map);
                  }
                })
            .named(
                "ForwardingNavigableMap[SafeTreeMap] with no comparator and standard "
                    + "implementations")
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.KNOWN_ORDER,
                MapFeature.ALLOWS_NULL_VALUES,

# FastAPI CLI

**FastAPI CLI** 是一個命令列程式，能用來運行你的 FastAPI 應用程式、管理你的 FastAPI 專案等。

當你安裝 FastAPI（例如使用 `pip install "fastapi[standard]"`），它會包含一個叫做 `fastapi-cli` 的套件，這個套件提供了 `fastapi` 命令。

要運行你的 FastAPI 應用程式來進行開發，你可以使用 `fastapi dev` 命令：

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>

// implementation-specific way and writes the result to standard error.
// Print is useful for bootstrapping and debugging; it is not guaranteed
// to stay in the language.
func print(args ...Type)

// The println built-in function formats its arguments in an
// implementation-specific way and writes the result to standard error.
// Spaces are always added between arguments and a newline is appended.

		return "", false, "", "", fmt.Errorf(format, args...)
	}
	goTool, err := goTool()
	if err != nil {
		return errorf("%w", err)
	}
	cmd := exec.Command(goTool, "list", "-e", "-f", "{{.ImportPath}}:{{.Standard}}{{with .Module}}:{{.Path}}:{{.Dir}}{{end}}", ".")
	out, err := cmd.Output()
	if err != nil {
		if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
			return errorf("%v: %s", cmd, ee.Stderr)
		}

 * ClassToInstanceMap}</a>.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@J2ktIncompatible
@GwtIncompatible
@SuppressWarnings("serial") // using writeReplace instead of standard serialization
public final class MutableClassToInstanceMap<B extends @Nullable Object>
    extends ForwardingMap<Class<? extends @NonNull B>, B>
    implements ClassToInstanceMap<B>, Serializable {

  /**

  }

  /**
   * Returns the <a
   * href="http://en.wikipedia.org/wiki/Standard_deviation#Corrected_sample_standard_deviation">
   * corrected sample standard deviation</a> of the values. If this dataset is a sample drawn from a
   * population, this is an estimator of the population standard deviation of the population which
   * is less biased than {@link #populationStandardDeviation()} (the unbiased estimator depends on