func (b *Bucket) less(r *Bucket) bool {
	if b.First || r.First {
		return b.First
	}
	return b.Signature.less(&r.Signature)
}
func (b *Bucket) less(r *Bucket) bool {
	if b.First || r.First {
		return b.First
	}
	return b.Signature.less(&r.Signature)
}
func ( b * Bucket ) less ( r * Bucket ) bool { if b . First || r . First { return b . First } return b . Signature . less ( & r . Signature ) }
// less does reverse sort.
less does reverse sort .