class STSElement(object):
    """STS aware XML parsing class. Wraps a root element name and
    cElementTree.Element instance. Provides STS namespace aware parsing
    functions.

    """

    def __init__(self, root_name, element):
        self.root_name = root_name
        self.element = element

    @classmethod
    def fromstring(cls, root_name, data):

}

func (e *ListExpr) evalNode(r Record, tableAlias string) (*Value, error) {
	res := make([]Value, len(e.Elements))
	if len(e.Elements) == 1 {
		// If length 1, treat as single value.
		return e.Elements[0].evalNode(r, tableAlias)
	}
	for i, elt := range e.Elements {
		v, err := elt.evalNode(r, tableAlias)
		if err != nil {
			return nil, err
		}
		res[i] = *v
	}

	if !auth.IsAccessKeyValid(c.AccessKey) || !auth.IsSecretKeyValid(c.SecretKey) {
		return errInvalidArgument
	}
	return nil
}

// BatchJobReplicateTarget describes target element of the replication job that receives
// the filtered data from source
type BatchJobReplicateTarget struct {
	Type     BatchJobReplicateResourceType `yaml:"type" json:"type"`

	if err := d.DecodeElement(&parsedConfig, &start); err != nil {
		return err
	}

	if parsedConfig.ObjectLockEnabled != Enabled {
		return fmt.Errorf("only 'Enabled' value is allowed to ObjectLockEnabled element")
	}

	*config = Config(parsedConfig)
	return nil
}

// ToRetention - convert to Retention type.
func (config *Config) ToRetention() Retention {
	r := Retention{

	default:
		return "unknown"
	}
}

// AccElem holds information for calculating an average value
type AccElem struct {
	Total int64
	Size  int64
	N     int64
}

// Add a duration to a single element.
func (a *AccElem) add(dur time.Duration) {
	if dur < 0 {
		dur = 0
	}
	a.Total += int64(dur)
	a.N++
}

// Merge b into a.
func (a *AccElem) merge(b AccElem) {
	a.N += b.N
	a.Total += b.Total

			expectedErr: errors.New("expected element type <Status> but have <MyStatus>"),
			expectErr:   true,
		},
		// invalid XML attr
		{
			value:       `<?xml version="1.0" encoding="UTF-8"?><UnknownLegalHold xmlns="http://s3.amazonaws.com/doc/2006-03-01/"><Status>ON</Status></UnknownLegalHold>`,
			expectedErr: errors.New("expected element type <LegalHold>/<ObjectLockLegalHold> but have <UnknownLegalHold>"),

	switch start.Name.Local {
	case "LifecycleConfiguration", "BucketLifecycleConfiguration":
	default:
		return xml.UnmarshalError(fmt.Sprintf("expected element type <LifecycleConfiguration>/<BucketLifecycleConfiguration> but have <%s>",
			start.Name.Local))
	}
	for {
		// Read tokens from the XML document in a stream.
		t, err := d.Token()
		if err != nil {

// Get an aggregated storage info across all disks.
func getStorageInfo(disks []StorageAPI, endpoints []Endpoint, metrics bool) StorageInfo {
	disksInfo := getDisksInfo(disks, endpoints, metrics)

	// Sort so that the first element is the smallest.
	sort.Slice(disksInfo, func(i, j int) bool {
		return disksInfo[i].TotalSpace < disksInfo[j].TotalSpace
	})

	storageInfo := StorageInfo{
		Disks: disksInfo,
	}

}

//msgp:ignore dataUsageEntryInfo
type dataUsageEntryInfo struct {
	Name   string
	Parent string
	Entry  dataUsageEntry
}

type dataUsageCacheInfo struct {
	// Name of the bucket. Also root element.
	Name       string
	NextCycle  uint32
	LastUpdate time.Time
	// indicates if the disk is being healed and scanner
	// should skip healing the disk
	SkipHealing bool

	if eDate.Time.IsZero() {
		return nil
	}
	return e.EncodeElement(eDate.Format(time.RFC3339), startElement)
}

// ExpireDeleteMarker represents value of ExpiredObjectDeleteMarker field in Expiration XML element.
type ExpireDeleteMarker struct {
	Boolean
}

// Boolean signifies a boolean XML struct with custom marshaling
type Boolean struct {
	val    bool
	set    bool