if err != nil {
		return err
	}

	eventData, eErr := target.store.Get(key)
	if eErr != nil {
		// The last event key in a successful batch will be sent in the channel atmost once by the replayEvents()
		// Such events will not exist and wouldve been already been sent successfully.
		if os.IsNotExist(eErr) {
			return nil
		}
		return eErr
	}

	if err := target.send(eventData); err != nil {

	values := make(url.Values)
	values.Set(peerRESTSize, strconv.Itoa(opts.objectSize))
	values.Set(peerRESTConcurrent, strconv.Itoa(opts.concurrency))
	values.Set(peerRESTDuration, opts.duration.String())
	values.Set(peerRESTStorageClass, opts.storageClass)
	values.Set(peerRESTBucket, opts.bucketName)
	values.Set(peerRESTEnableSha256, strconv.FormatBool(opts.enableSha256))

// ChecksumType contains information about the checksum type.
type ChecksumType uint32

const (

	// ChecksumTrailing indicates the checksum will be sent in the trailing header.
	// Another checksum type will be set.
	ChecksumTrailing ChecksumType = 1 << iota

	// ChecksumSHA256 indicates a SHA256 checksum.
	ChecksumSHA256
	// ChecksumSHA1 indicates a SHA-1 checksum.
	ChecksumSHA1

If an incoming request does not validate correctly then a `400` response will be sent.

## `GZipMiddleware`

Handles GZip responses for any request that includes `"gzip"` in the `Accept-Encoding` header.

The middleware will handle both standard and streaming responses.

		header := w.Header()
		header.Set("X-XSS-Protection", "1; mode=block")                                // Prevents against XSS attacks
		header.Set("X-Content-Type-Options", "nosniff")                                // Prevent mime-sniff
		header.Set("Strict-Transport-Security", "max-age=31536000; includeSubDomains") // HSTS mitigates variants of MITM attacks

		// Previously, this value was set right before a response was sent to

			}
			return err
		}
	}

	eventData, eErr := target.store.Get(key)
	if eErr != nil {
		// The last event key in a successful batch will be sent in the channel atmost once by the replayEvents()
		// Such events will not exist and wouldve been already been sent successfully.
		if os.IsNotExist(eErr) {
			return nil
		}
		return eErr
	}

	if err := target.send(eventData); err != nil {
		if IsConnErr(err) {

					done()
					if ok {
						root := cache.find(bucket)
						if root == nil {
							// We dont have usage information for this bucket in this
							// set, go to the next set
							continue
						}

						for id, usageInfo := range cache.flattenChildrens(*root) {
							prefix := decodeDirObject(strings.TrimPrefix(id, bucket+slashSeparator))

		sys.metadataMap[buckets[i]] = meta
	}
	sys.Unlock()

	for i, meta := range bucketMetas {
		if errs[i] != nil {
			continue
		}
		globalEventNotifier.set(buckets[i], meta)   // set notification targets
		globalBucketTargetSys.set(buckets[i], meta) // set remote replication targets
	}
}

func (sys *BucketMetadataSys) refreshBucketsMetadataLoop(ctx context.Context) {
	const bucketMetadataRefresh = 15 * time.Minute

///

That would generate a `dict` with only the data that was set when creating the `item` model, excluding default values.

Then you can use this to generate a `dict` with only the data that was set (sent in the request), omitting default values:

//// tab | Python 3.10+

```Python hl_lines="32"
{!> ../../docs_src/body_updates/tutorial002_py310.py!}

You can use them to add a specific set of permissions to a JWT token.

Then you can give this token to a user directly or a third party, to interact with your API with a set of restrictions.

You can learn how to use them and how they are integrated into **FastAPI** later in the **Advanced User Guide**.

## Recap