code: func NewExtractor(source string) (Extractor, error) {
  	for suffix, extractor := range Extractors {
  		if strings.HasSuffix(source, suffix) {
  			return extractor, nil
  		}
  	}
  	return nil, fmt.Errorf("no extractor implemented yet for %s", source)
  }
docs: // NewExtractor creates a new extractor matching the source file name