code: func (fs *statikFS) Open(name string) (http.File, error) {
  	name = strings.Replace(name, "//", "/", -1)
  	if f, ok := fs.files[name]; ok {
  		return newHTTPFile(f), nil
  	}
  	return nil, os.ErrNotExist
  }
docs: // Open returns a file matching the given file name, or os.ErrNotExists if
  // no file matching the given file name is found in the archive.
  // If a directory is requested, Open returns the file named "index.html"
  // in the requested directory, if that file exists.