code: func joinPathComp(prefix, suffix string) string {
  	suffix = strings.TrimLeft(suffix, ".")
  	if prefix != "" && suffix != "" {
  		return prefix + "." + suffix
  	}
  	return prefix + suffix
  }
docs: // joinPathComp is a helper that ensures we combine path components with a dot
  // when it's appropriate to do so; prefix is the existing prefix and suffix is
  // the new component being added.
  //
  // It returns the joined prefix.