code: func newInternalFS(prefix string) http.FileSystem {
  	// Asset/AssetDir returns `fmt.Errorf("Asset %s not found")`,
  	// which does _not_ get mapped to 404 by `http.FileSystem`.
  	// Need to convert to `os.ErrNotExist` explicitly ourselves.
  	mapNotFound := func(err error) error {
  		if err != nil && strings.Contains(err.Error(), "not found") {
  			err = os.ErrNotExist
  		}
  		return err
  	}
  	return &assetfs.AssetFS{
  		Asset: func(path string) ([]byte, error) {
  			ret, err := Asset(path)
  			return ret, mapNotFound(err)
  		},
  		AssetDir: func(path string) ([]string, error) {
  			ret, err := AssetDir(path)
  			return ret, mapNotFound(err)
  		},
  		Prefix: prefix,
  	}
  }
docs: //go:generate go-bindata -nometadata -ignore .*_test\.|~$DOLLAR -pkg $GOPACKAGE -o bindata.go -prefix ../ ../lib/...