Wrapper interface

src/GridSearch.php

@@ -39,7 +39,7 @@
  * @package     Rubix/ML
  * @author      Andrew DalPino
  */
-class GridSearch implements Estimator, Learner, Parallel, Verbose, Persistable
+class GridSearch implements Wrapper, Learner, Parallel, Verbose, Persistable
 {
     use AutotrackRevisions, Multiprocessing, LoggerAware;
 

src/PersistentModel.php

@@ -21,7 +21,7 @@
  * @package     Rubix/ML
  * @author      Andrew DalPino
  */
-class PersistentModel implements Estimator, Learner, Probabilistic, Scoring
+class PersistentModel implements Wrapper, Learner, Probabilistic, Scoring
 {
     /**
      * The persistable base learner.

src/Pipeline.php

@@ -25,7 +25,7 @@
  * @package     Rubix/ML
  * @author      Andrew DalPino
  */
-class Pipeline implements Online, Probabilistic, Scoring, Persistable
+class Pipeline implements Online, Probabilistic, Scoring, Persistable, Wrapper
 {
     use AutotrackRevisions;
 

src/Wrapper.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Rubix\ML;
+
+/**
+ * Wrapper
+ *
+ * @category    Machine Learning
+ * @package     Rubix/ML
+ * @author      Andrew DalPino
+ */
+interface Wrapper extends Estimator
+{
+    /**
+     * Return the base estimator instance.
+     *
+     * @return Estimator
+     */
+    public function base(): Estimator;
+}