code: func (b *Blob) AsStaticFile() (sf StaticFile, ok bool) {
  	// TODO (marete) Add support for device files to
  	// Perkeep and change the implementation of StaticFile to
  	// reflect that.
  	t := b.ss.Type
  	if t == "file" || t == "symlink" || t == "fifo" || t == "socket" {
  		return StaticFile{b}, true
  	}
  
  	return
  }
docs: // AsStaticFile returns the Blob as a StaticFile if it represents
  // one. Otherwise, it returns false in the boolean parameter and the
  // zero value of StaticFile.