code: func (t *Tree) Root() (*File, error) {
  	if !t.haveRaw {
  		data, err := t.comp.scget(t.Score)
  		if err != nil {
  			return nil, err
  		}
  		if err := unpack(data, &t.raw); err != nil {
  			return nil, err
  		}
  		t.haveRaw = true
  	}
  
  	dir := &File{
  		t:   t,
  		dir: &t.raw,
  		n:   &nameNode{"/", node{IsTree: true}},
  	}
  	return dir, nil
  }
docs: // Root returns the File for the tree's root directory.