File adder

func (o *ContentAddOperation) add(fs files.File) (*AddedContent, error) {
	var contentType ContentType
	if fs.IsDirectory() {
		contentType = Directory
		for {
			f, err := fs.NextFile()
			if err == io.EOF {
				break
			} else if err != nil {
				return nil, err
			}
			if f != nil {
				if err = o.adder.AddFile(f); err != nil {
					return nil, err
				}
			}
		}
	} else {
		contentType = File
		if err := o.adder.AddFile(fs); err != nil {
			return nil, err
		}
	}

	node, err := o.adder.Finalize()

	if err != nil {
		return nil, err
	}
	err = o.adder.PinRoot()
	if err != nil {
		return nil, err
	}

	key, _ := node.Key()
	return &AddedContent{
		DagEntry:    node,
		ContentName: fs.FileName(),
		ContentType: contentType,
		Hash:        key.B58String(),
	}, nil
}