if a.ContainsDuplicateTag() {
		return errDuplicateTagKey
	}
	for _, t := range a.Tags {
		if err := t.Validate(); err != nil {
			return err
		}
	}
	return nil
}

// ContainsDuplicateTag - returns true if duplicate keys are present in And
func (a And) ContainsDuplicateTag() bool {
	x := make(map[string]struct{}, len(a.Tags))

	for _, t := range a.Tags {
		if _, has := x[t.Key]; has {
			return true
		}

		predCount++
	}
	if a.ObjectSizeLessThan > 0 {
		predCount++
	}

	if predCount < 2 {
		return errXMLNotWellFormed
	}

	if a.ContainsDuplicateTag() {
		return errDuplicateTagKey
	}
	for _, t := range a.Tags {
		if err := t.Validate(); err != nil {
			return err
		}
	}

	if a.ObjectSizeGreaterThan < 0 || a.ObjectSizeLessThan < 0 {
		return errXMLNotWellFormed
	}
	return nil
}