func NewDagModifier(from *mdag.Node, serv mdag.DAGService, spl chunk.BlockSplitter) (*DagModifier, error) {
	pbd, err := ft.FromBytes(from.Data)
	if err != nil {
		return nil, err
	}

	return &DagModifier{
		curNode:  from.Copy(),
		dagserv:  serv,
		pbdata:   pbd,
		splitter: spl,
	}, nil
}