### 3.1 Automatic removal of non current objects versions

A non-current object version is a version which is not the latest for a given object. It is possible to set up an automatic removal of non-current versions when a version becomes older than a given number of days.

e.g., To scan objects stored under `user-uploads/` prefix and remove versions older than one year.

```
{
    "Rules": [
        {
            "ID": "Removing all old versions",

		// the content implicitly for all versions, we can
		// avoid triggering another MRF heal for offline drives.
		if len(versions) == 0 {
			// Whether a disk was initially or becomes offline
			// during this upload, send it to the MRF list.
			for i := 0; i < len(onlineDisks); i++ {
				if onlineDisks[i] != nil && onlineDisks[i].IsOnline() {
					continue
				}

	return ""
}

// MarshalXML - encodes to XML data.
func (name Name) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	return e.EncodeElement(name.String(), start)
}

// UnmarshalXML - decodes XML data.
func (name *Name) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	var s string
	if err := d.DecodeElement(&s, &start); err != nil {
		return err
	}

	eventName, err := ParseName(s)

	New: func() interface{} {
		// io.Discard is just used to create the writer. Actual destination
		// writer is set later by Reset() before using it.
		return bufio.NewWriter(xioutil.Discard)
	},
}

// UnmarshalXML - decodes XML data.
func (c *CompressionType) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	var s string
	if err := d.DecodeElement(&s, &start); err != nil {
		return errMalformedXML(err)
	}

		if err := e.EncodeElement(d.StorageClass, xml.StartElement{Name: xml.Name{Local: "StorageClass"}}); err != nil {
			return err
		}
	}
	return e.EncodeToken(xml.EndElement{Name: start.Name})
}

// UnmarshalXML - decodes XML data.
func (d *Destination) UnmarshalXML(dec *xml.Decoder, start xml.StartElement) (err error) {
	// Make subtype to avoid recursive UnmarshalXML().
	type destination Destination
	dest := destination{}

If the remote handler is blocked on a send, and the client is trying to send without the remote receiving, 
the operation would become deadlocked if the channels are full.

### Typed handlers

Typed handlers are handlers that have a specific type for the request and response payloads.

```go
    // Create a typed handler.

	return claims
}

func getClaimsFromTokenWithSecret(token, secret string) (map[string]interface{}, error) {
	// JWT token for x-amz-security-token is signed with admin
	// secret key, temporary credentials become invalid if
	// server admin credentials change. This is done to ensure
	// that clients cannot decode the token using the temp
	// secret keys and generate an entirely new claim by essentially

	}

	err = s.adm.SetPolicy(ctx, policy, "test-group", true)
	if err != nil {
		c.Fatalf("Unable to set policy: %v", err)
	}

	// confirm that the user is able to access the bucket - permission comes
	// from group.
	c.mustListObjects(ctx, uClient, bucket)

	// Create STS user.
	assumeRole := cr.STSAssumeRole{
		Client:      s.TestSuiteCommon.client,
		STSEndpoint: s.endPoint,

	RetryInterval time.Duration
}

// GetLock tries to get a write lock on dm before the timeout elapses.
//
// If the lock is already in use, the calling go routine
// blocks until either the mutex becomes available and return success or
// more time has passed than the timeout value and return false.
func (dm *DRWMutex) GetLock(ctx context.Context, cancel context.CancelFunc, id, source string, opts Options) (locked bool) {

	set    bool
	Unused struct{} // Needed for GOB compatibility
}

// UnmarshalXML - decodes XML data.
func (p *Prefix) UnmarshalXML(d *xml.Decoder, start xml.StartElement) (err error) {
	var s string
	if err = d.DecodeElement(&s, &start); err != nil {
		return err
	}
	*p = Prefix{string: s, set: true}
	return nil
}

// MarshalXML - decodes XML data.
func (p Prefix) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {