「情境管理器」是那些你可以在 `with` 陳述式中使用的 Python 物件。

例如，[你可以用 `with` 來讀取檔案](https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files)：

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

在底層，`open("./somefile.txt")` 會建立一個稱為「情境管理器」的物件。

當 `with` 區塊結束時，它會確保關閉檔案，即使發生了例外也一樣。

當你建立一個含 `yield` 的相依時，**FastAPI** 會在內部為它建立一個情境管理器，並與其他相關工具結合。

	}
}

func newXferStats() *XferStats {
	return &XferStats{
		measure: newRateMeasurement(time.Now()),
		sma:     newSMA(50),
	}
}

func (rx *XferStats) String() string {
	return fmt.Sprintf("curr=%f avg=%f, peak=%f", rx.curr(), rx.Avg, rx.Peak)
}

func (rx *XferStats) curr() float64 {
	if rx.measure == nil {
		return 0.0
	}
	return rx.measure.getExpMovingAvgBytesPerSecond()
}

		if deploymentID != formats[i].ID {
			return nil, fmt.Errorf("all pools must have same deployment ID - expected %s, got %s for pool(%s)", deploymentID, formats[i].ID, humanize.Ordinal(i+1))
		}

		bootstrapTrace(fmt.Sprintf("newErasureSets: initializing %s pool", humanize.Ordinal(i+1)), func() {
			z.serverPools[i], err = newErasureSets(ctx, ep, storageDisks[i], formats[i], commonParityDrives, i)
		})
		if err != nil {
			return nil, err

### typing 模块 { #typing-module }

在一些额外的用例中，你可能需要从标准库的 `typing` 模块导入内容。比如当你想声明“任意类型”时，可以使用 `typing` 中的 `Any`：

```python
from typing import Any


def some_function(data: Any):
    print(data)
```

### 泛型类型 { #generic-types }

有些类型可以在方括号中接收“类型参数”（type parameters），用于声明其内部值的类型。比如“字符串列表”可以写为 `list[str]`。

这些能接收类型参数的类型称为“泛型类型”（Generic types）或“泛型”（Generics）。

你可以把相同的内建类型作为泛型使用（带方括号和内部类型）：

errors.invalid_header_for_request_file=Invalid header line: {0}
errors.could_not_delete_logged_in_user=You cannot delete a user who is logged in.
errors.unauthorized_request=Unauthorized request.
errors.failed_to_print_thread_dump=Failed to print a thread dump.
errors.file_is_not_supported={0} is not supported.
errors.plugin_file_is_not_found={0} is not found.
errors.failed_to_install_plugin=Failed to install {0}.

errors.invalid_header_for_request_file=Invalid header line: {0}
errors.could_not_delete_logged_in_user=You cannot delete a user who is logged in.
errors.unauthorized_request=Unauthorized request.
errors.failed_to_print_thread_dump=Failed to print a thread dump.
errors.file_is_not_supported={0} is not supported.
errors.plugin_file_is_not_found={0} is not found.
errors.failed_to_install_plugin=Failed to install {0}.

		if envOnly {
			key = config.EnvPrefix + strings.ToTitle(subSys) + config.EnvWordDelimiter + strings.ToTitle(madmin.EnableKey)
		}
		help = append(help, config.HelpKV{
			Key:         key,
			Description: fmt.Sprintf("enable %s target, default is 'off'", subSys),
			Optional:    false,
			Type:        "on|off",
		})
	}

	for _, hkv := range h {
		key := hkv.Key
		if envOnly {

!important;\n    display: inline-flex !important;\n  }\n}\n\n@media print {\n  .d-print-none {\n    display: none !important;\n  }\n  .d-print-inline {\n    display: inline !important;\n  }\n  .d-print-inline-block {\n    display: inline-block !important;\n  }\n  .d-print-block {\n    display: block !important;\n  }\n  .d-print-table {\n    display: table !important;\n  }\n  .d-print-table-row {\n    display: table-row !important;\n  }\n  .d-print-table-cell {\n    display: table-cell !important;\n  }\n  .d-print-flex...

- kubectl: `--use-openapi-print-columns` has been deprecated in favor of `--server-print`, and will be removed in a future version. ([#65601](https://github.com/kubernetes/kubernetes/pull/65601), [@liggitt](https://github.com/liggitt))

////

//// tab | Info

... However, quotes inside code snippets must stay as is.

////

## code blocks { #code-blocks }

//// tab | Test

A Bash code example...

```bash
# Print a greeting to the universe
echo "Hello universe"
```

...and a console code example...

```console
$ <font color="#4E9A06">fastapi</font> run <u style="text-decoration-style:solid">main.py</u>