code: func IsValidPathSegmentPrefix(name string) (bool, string) {
  	for _, illegalContent := range NameMayNotContain {
  		if strings.Contains(name, illegalContent) {
  			return false, fmt.Sprintf(`name may not contain %q`, illegalContent)
  		}
  	}
  
  	return true, ""
  }
docs: // IsValidPathSegmentPrefix validates the name can be used as a prefix for a name which will be encoded as a path segment
  // It does not check for exact matches with disallowed names, since an arbitrary suffix might make the name valid