code: func (b *Box) Open(name string) (http.File, error) {
  	plog.Debug(b, "Open", "name", name)
  	f, err := b.Resolve(name)
  	if err != nil {
  		if len(filepath.Ext(name)) == 0 {
  			return b.openWoExt(name)
  		}
  		return f, err
  	}
  	f, err = file.NewFileR(name, f)
  	plog.Debug(b, "Open", "name", f.Name(), "file", f.Name())
  	return f, err
  }
docs: // Open returns a File using the http.File interface