This code is something you can actually use in your application, save the password hashes in your database, etc.

We are going to start from where we left in the previous chapter and increment it.

## About JWT { #about-jwt }

JWT means "JSON Web Tokens".

It's a standard to codify a JSON object in a long dense string without spaces. It looks like this:

```

        // Assert
        assertEquals(42, n);
        ArgumentCaptor<Smb2IoctlRequest> cap = ArgumentCaptor.forClass(Smb2IoctlRequest.class);
        verify(tree).send(cap.capture(), eq(RequestParam.NO_RETRY));
        assertNotNull(cap.getValue()); // captured request should be present
    }

    @Test
    @DisplayName("sendrecv uses TransactNamedPipe when PIPE_TYPE_TRANSACT is set")

  static final Integer N3 = 3;
  static final Integer N4 = 4;
  static final Integer N5 = 5;
  static final Integer NODE_NOT_IN_GRAPH = 1000;

  // TODO(user): Consider separating Strings that we've defined here to capture
  // identifiable substrings of expected error messages, from Strings that we've defined
  // here to provide error messages.
  // TODO(user): Some Strings used in the subclasses can be added as static Strings
  // here too.

			<li class="nav-item has-treeview <c:if test="${param.menuCategoryType=='system'}">menu-open</c:if>">
				<a href="#" class="nav-link <c:if test="${param.menuCategoryType=='system'}">active</c:if>">
					<i class='nav-icon fa fa-laptop' aria-hidden="true"></i>
					<p>
						<la:message key="labels.menu_system" />
						<i class="right fas fa-angle-left"></i>
					</p>
				</a>
				<ul class="nav nav-treeview">

rit}.table>thead{vertical-align:bottom}.table-group-divider{border-top:calc(var(--bs-border-width) * 2) solid currentcolor}.caption-top{caption-side:top}.table-sm>:not(caption)>*>*{padding:.25rem .25rem}.table-bordered>:not(caption)>*{border-width:var(--bs-border-width) 0}.table-bordered>:not(caption)>*>*{border-width:0 var(--bs-border-width)}.table-borderless>:not(caption)>*>*{border-bottom-width:0}.table-borderless>:not(:first-child){border-top-width:0}.table-striped>tbody>tr:nth-of-type(odd)>...

// 在此之后这个环境变量将不会依然存在
$ python main.py

Hello World from Python
```

</div>

/// tip

你可以在 <a href="https://12factor.net/zh_cn/config" class="external-link" target="_blank">The Twelve-Factor App: 配置</a>中了解更多信息。

///

## 类型和验证

这些环境变量只能处理**文本字符串**，因为它们是处于 Python 范畴之外的，必须与其他程序和操作系统的其余部分兼容（甚至与不同的操作系统兼容，如 Linux、Windows、macOS）。

这意味着从环境变量中读取的**任何值**在 Python 中都将是一个 `str`，任何类型转换或验证都必须在代码中完成。

          // requireNonNull is safe because right must exist in order to get a negative factor.
          requireNonNull(right);
          if (right.balanceFactor() > 0) {
            right = right.rotateRight();
          }
          return rotateLeft();
        case 2:
          // requireNonNull is safe because left must exist in order to get a positive factor.
          requireNonNull(left);
          if (left.balanceFactor() < 0) {

 * }
 *
 * <p>It is guaranteed that {@code encoding.decode(encoding.encode(x))} is always equal to {@code
 * x}, but the reverse does not necessarily hold.
 *
 * <table>
 * <caption>Encodings</caption>
 * <tr>
 * <th>Encoding
 * <th>Alphabet
 * <th>{@code char:byte} ratio
 * <th>Default padding
 * <th>Comments
 * <tr>
 * <td>{@link #base16()}
 * <td>0-9 A-F
 * <td>2.00
 * <td>N/A

command: [ "/bin/sh", "-ce", "/usr/bin/docker-entrypoint.sh minio -S {{ .Values.certsPath }} server --address :{{ .Values.minioAPIPort }} --console-address :{{ .Values.minioConsolePort }} {{- range $i := until $poolCount }}{{ $factor := mul $i $nodeCount }}{{ $endIndex := add $factor $nodeCount }}{{ $beginIndex := mul $i $nodeCount }} {{ $scheme }}://{{ template `minio.fullname` $ }}-{{ `{` }}{{ $beginIndex }}...{{ sub $endIndex 1 }}{{ `}`}}.{{ template `minio.fullname` $ }}-svc.{{ $.Release.Namespace...

   * can hold setSize elements with the desired load factor. Always returns at least setSize + 2.
   */
  // TODO(cpovirk): Move to Hashing or something, since it's used elsewhere in the Android version.
  static int chooseTableSize(int setSize) {
    setSize = max(setSize, 2);
    // Correct the size for open addressing to match desired load factor.
    if (setSize < CUTOFF) {