anchor.diff:    * POST /contactdb/recipients/search
     * Note that this endpoint exists, providing more robust, segmented search. However, I don't see support for it in any of the official libraries, so I'm not going to bother to put it together here, unless there's a need for it.
     */
  +
  +  /**
  +  * @hint Helper method, which allows for passing in the recipient id or email address and returns the id, which is needed. The recipient Id is a URL-safe base64 encoding of the recipient's lower cased email address
  +  */
  +  private string function returnRecipientId( required string id ) {
  +    return isValid( 'email', id ) ? toBase64( id ) : id;
  +  }
   
     /**
     * Contacts API - Custom Fields
  
positive.code:   /**
    * https://sendgrid.api-docs.io/v3.0/contacts-api-recipients/delete-a-recipient
    * @hint This endpoint allows you to delete a single recipient with the given ID from your contact database.
    */
    public struct function deleteRecipient( required string id ) {
      return apiCall( 'DELETE', "/contactdb/recipients/#id#" );
    }
  
    /**
  
negative.code:   * @hint This endpoint allows you to retrieve the lists that a given recipient belongs to.
    */
    public struct function listListsByRecipient( required string id ) {
      return apiCall( 'GET', "/contactdb/recipients/#returnRecipientId( id )#/lists" );
    }
  
    /**
  