func VolumeUnit(tag VolumeTag) (UnitTag, bool) {
	id := tag.Id()
	pos := strings.LastIndex(id, "/")
	if pos == -1 {
		return UnitTag{}, false
	}
	id = id[:pos]
	if !IsValidUnit(id) {
		return UnitTag{}, false
	}
	return NewUnitTag(id[:pos]), true
}
// VolumeUnit returns the unit component of the volume
// tag, and a boolean indicating whether or not there is a
// unit component.
VolumeUnit returns the unit component of the volume
tag, and a boolean indicating whether or not there is a
unit component.
// VolumeUnit returns the unit component of the volume // tag and a boolean indicating whether or not there is a // unit component .
func VolumeUnit(tag VolumeTag) (UnitTag, bool) {
	id := tag.Id()
	pos := strings.LastIndex(id, "/")
	if pos == -1 {
		return UnitTag{}, false
	}
	id = id[:pos]
	if !IsValidUnit(id) {
		return UnitTag{}, false
	}
	return NewUnitTag(id[:pos]), true
}
func VolumeUnit ( tag VolumeTag ) ( UnitTag , bool ) { id := tag . Id ( ) pos := strings . LastIndex ( id , " " ) if pos == - 1 { return UnitTag { } , false } id = id [ : pos ] if ! IsValidUnit ( id ) { return UnitTag { } , false } return NewUnitTag ( id [ : pos ] ) , true }
VolumeUnit returns the unit component of the volume
tag, and a boolean indicating whether or not there is a
unit component.
VolumeUnit returns the unit component of the volume tag and a boolean indicating whether or not there is a unit component .