func mustGetMetadata(key string) []byte {
	b, err := getMetadata(key)
	if err != nil {
		panic(fmt.Sprintf("Metadata fetch failed for '%s': %v", key, err))
	}
	return b
}
func mustGetMetadata(key string) []byte {
	b, err := getMetadata(key)
	if err != nil {
		panic(fmt.Sprintf("Metadata fetch failed for '%s': %v", key, err))
	}
	return b
}
func mustGetMetadata ( key string ) [ ] byte { b , err := getMetadata ( key ) if err != nil { panic ( fmt . Sprintf ( " " , key , err ) ) } return b }
// TODO(dsymonds): Do we need to support default values, like Python?
TODO ( dsymonds ) : Do we need to support default values like Python?