      Enter a [custom
      model](https://cloud.ibm.com/docs/services/natural-language-understanding?topic=natural-language-understanding-customizing)
      ID to override the standard categories model.
-     The custom categories experimental feature will be retired on 19 December 2019. On that date, deployed custom
-     categories models will no longer be accessible in Natural Language Understanding. The feature will be removed from
-     Knowledge Studio on an earlier date. Custom categories models will no longer be accessible in Knowledge Studio on
-     17 December 2019.
      */
     public var model: String?
 

/**
 * (C) Copyright IBM Corp. 2020.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.


    /**
     Initialize a `CategoriesOptions` with member variables.
     - parameter explanation: Set this to `true` to return explanations for each categorization. **This is available
       only for English categories.**.
     - parameter limit: Maximum number of categories to return.
     - parameter model: Enter a [custom
       model](https://cloud.ibm.com/docs/services/natural-language-understanding?topic=natural-language-understanding-customizing)
       ID to override the standard categories model.
     - returns: An initialized `CategoriesOptions`.
     */
    public init(
