code: func MatchesUsername(namespace, name string, username string) bool {
  	if !strings.HasPrefix(username, ServiceAccountUsernamePrefix) {
  		return false
  	}
  	username = username[len(ServiceAccountUsernamePrefix):]
  
  	if !strings.HasPrefix(username, namespace) {
  		return false
  	}
  	username = username[len(namespace):]
  
  	if !strings.HasPrefix(username, ServiceAccountUsernameSeparator) {
  		return false
  	}
  	username = username[len(ServiceAccountUsernameSeparator):]
  
  	return username == name
  }
docs: // MatchesUsername checks whether the provided username matches the namespace and name without
  // allocating. Use this when checking a service account namespace and name against a known string.