code: func (e *Signer) getTokens() map[string]string {
  	ret := map[string]string{}
  	secretObjs := e.listSecrets()
  	for _, secret := range secretObjs {
  		tokenID, tokenSecret, ok := validateSecretForSigning(secret)
  		if !ok {
  			continue
  		}
  
  		// Check and warn for duplicate secrets. Behavior here will be undefined.
  		if _, ok := ret[tokenID]; ok {
  			// This should never happen as we ensure a consistent secret name.
  			// But leave this in here just in case.
  			klog.V(1).Infof("Duplicate bootstrap tokens found for id %s, ignoring on in %s/%s", tokenID, secret.Namespace, secret.Name)
  			continue
  		}
  
  		// This secret looks good, add it to the list.
  		ret[tokenID] = tokenSecret
  	}
  
  	return ret
  }
docs: // getTokens returns a map of tokenID->tokenSecret. It ensures the token is
  // valid for signing.