環境変数はPythonの**外側**（ターミナル、またはその他の方法）で作成し、その後に**Pythonで読み取る**こともできます。

例えば、以下のような`main.py`ファイルを用意します:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | 豆知識

[`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) の第2引数は、返されるデフォルト値です。

指定しない場合、デフォルトは`None`ですが、ここでは使用するデフォルト値として`"World"`を指定しています。

///

「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。

### Synchronous Get ([.kt][SynchronousGetKotlin], [.java][SynchronousGetJava])

Download a file, print its headers, and print its response body as a string.

    (Exception: if the Program itself is interactive but does not
    normally print such an announcement, your work based on the Program
    is not required to print an announcement.)

These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program, and
can be reasonably considered independent and separate works in

    - [Container Images](#container-images-16)
  - [Changelog since v1.26.0](#changelog-since-v1260)
  - [Known Issues](#known-issues)
    - [The PreEnqueue extension point doesn't work for Pods going to activeQ through backoffQ](#the-preenqueue-extension-point-doesnt-work-for-pods-going-to-activeq-through-backoffq)
  - [Urgent Upgrade Notes](#urgent-upgrade-notes)

        emptyMappingFile.manager(dictionaryManager);

        PagingList<CharMappingItem> result = emptyMappingFile.selectList(0, 10);

        // Debug: print what we actually got
        if (result.size() > 0) {
            for (CharMappingItem item : result) {
                System.out.println("Unexpected item: " + item.toLineString());
            }
        }

- Unreserve extension point for scheduler plugins is merged into Reserve extension point ([#92200](https://github.com/kubernetes/kubernetes/pull/92200), [@adtac](https://github.com/adtac)) [SIG Scheduling and Testing]

       *
       * We store `localFuturesOrNull` inside the listener because `this.futures` might be nulled
       * out by the time the listener runs for the final future -- at which point we need to check
       * all inputs for exceptions *if* we're collecting values. If we're not, then the listener
       * doesn't need access to the futures again, so we can just pass `null`.
       *

        // Then
        int bodyOffset = Smb2Constants.SMB2_HEADER_LENGTH;
        int securityBufferOffset = SMBUtil.readInt2(buffer, bodyOffset + 12);

        // The offset should point to the location after the fixed structure (relative to header start)
        int expectedOffset = Smb2Constants.SMB2_HEADER_LENGTH + 24;
        while ((expectedOffset % 8) != 0) {
            expectedOffset++; // Account for pad8

    public void addDocumentMappingRewriteRule(final UnaryOperator<String> rule) {
        docMappingRewriteRuleList.add(rule);
    }

    /**
     * Updates index aliases to point to a new index.
     *
     * @param newIndex the new index to point aliases to
     * @return true if the alias update was successful, false otherwise
     */
    public boolean updateAlias(final String newIndex) {