code: func (l *PacketList) PushBackList(other *PacketList) {
  	l.lazyInit()
  	for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
  		l.insertValue(e.Value, l.root.prev)
  	}
  }
docs: // PushBackList inserts a copy of an other list at the back of list l.
  // The lists l and other may be the same. They must not be nil.