For example, if you want to read or manipulate the request body before it is processed by your application.

/// danger

This is an "advanced" feature.

If you are just starting with **FastAPI** you might want to skip this section.

///

## Use cases { #use-cases }

Some use cases include:

* Converting non-JSON request bodies to JSON (e.g. [`msgpack`](https://msgpack.org/index.html)).

}

// NewDummyDataGen returns a ReadSeeker over the first `totalLength`
// bytes from the infinite stream consisting of repeated
// concatenations of `alphabets`.
//
// The skipOffset (generally = 0) can be used to skip a given number
// of bytes from the beginning of the infinite stream. This is useful
// to compare such streams of bytes that may be split up, because:
//
// Given the function:
//
//	f := func(r io.Reader) string {

//     compress: true # S2/Snappy compressed archive
//     smallerThan: 5MiB # create archive for all objects smaller than 5MiB
//     skipErrs: false # skips any source side read() errors

// BatchJobSnowball describes the snowball feature when replicating objects from a local source to a remote target
type BatchJobSnowball struct {
	line, col   int

     *
     * @param parent the parent element (e.g., dependency or plugin)
     * @param groupId the groupId value
     * @param artifactId the artifactId value
     * @param version the version value (can be null to skip)
     *
     */
    public static void addGAVElements(Element parent, String groupId, String artifactId, String version) {
        insertContentElement(parent, GROUP_ID, groupId);

		{"ChecksumSHA256-full-object", ChecksumSHA256, true, true}, // SHA256 does not support full object
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			// Skip invalid cases where SHA1 or SHA256 is used with full object
			if (tt.checksum.Is(ChecksumSHA1) || tt.checksum.Is(ChecksumSHA256)) && tt.fullobj {
				// Validate that NewChecksumType correctly marks these as invalid

But first, let's check some small concepts.

## In a hurry? { #in-a-hurry }

If you don't care about any of these terms and you just need to add security with authentication based on username and password *right now*, skip to the next chapters.

## OAuth2 { #oauth2 }

OAuth2 is a specification that defines several ways to handle authentication and authorization.

It is quite an extensive specification and covers several complex use cases.

            // Verify the path is correctly encoded in UTF-16LE
            ByteBuffer bb = ByteBuffer.wrap(dst).order(ByteOrder.LITTLE_ENDIAN);
            bb.getShort(); // Skip referral level

            byte[] pathBytes = path.getBytes(StandardCharsets.UTF_16LE);
            byte[] encodedPath = new byte[pathBytes.length];
            bb.get(encodedPath);

            Arrays.fill(buffer, (byte) 0xFF);

            lock.encode(buffer, 0);

            // Reserved field bytes are not modified by the encode method
            // The implementation just skips these bytes without writing zeros
            assertEquals(-1, SMBUtil.readInt4(buffer, 20));
        }
    }

    @Nested
    @DisplayName("Flag Constants Tests")
    class FlagConstantsTests {

				// Determine if os.NotExist error is because of
				// baseDir's parent being present, retry it once such
				// that the MkdirAll is retried once for the parent
				// of dirPath.
				// Because it is worth a retry to skip a different
				// baseDir which is slightly higher up the depth.
				nbaseDir := path.Dir(baseDir)
				if baseDir != "" && nbaseDir != "" && nbaseDir != SlashSeparator {
					baseDir = nbaseDir
				}
				continue

	args := Args{}

	if err := s.CheckValidKeys(config.PolicyPluginSubSys, nil); err != nil {
		return args, err
	}

	getCfg := func(cfgParam string) string {
		// As parameters are already validated, we skip checking
		// if the config param was found.
		val, _, _ := s.ResolveConfigParam(config.PolicyPluginSubSys, config.Default, cfgParam, false)
		return val
	}

	pluginURL := getCfg(URL)
	if pluginURL == "" {