diff --git a/src/Phpml/Classification/KNearestNeighbors.php b/src/Phpml/Classification/KNearestNeighbors.php
index f1a87cf..95ebeaf 100644
--- a/src/Phpml/Classification/KNearestNeighbors.php
+++ b/src/Phpml/Classification/KNearestNeighbors.php
@@ -35,7 +35,7 @@ class KNearestNeighbors implements Classifier
 
         $this->k = $k;
         $this->samples = [];
-        $this->labels = [];
+        $this->targets = [];
         $this->distanceMetric = $distanceMetric;
     }
 
@@ -48,10 +48,10 @@ class KNearestNeighbors implements Classifier
     {
         $distances = $this->kNeighborsDistances($sample);
 
-        $predictions = array_combine(array_values($this->labels), array_fill(0, count($this->labels), 0));
+        $predictions = array_combine(array_values($this->targets), array_fill(0, count($this->targets), 0));
 
         foreach ($distances as $index => $distance) {
-            ++$predictions[$this->labels[$index]];
+            ++$predictions[$this->targets[$index]];
         }
 
         arsort($predictions);
diff --git a/src/Phpml/Classification/NaiveBayes.php b/src/Phpml/Classification/NaiveBayes.php
index 9726b40..3e7d819 100644
--- a/src/Phpml/Classification/NaiveBayes.php
+++ b/src/Phpml/Classification/NaiveBayes.php
@@ -19,7 +19,7 @@ class NaiveBayes implements Classifier
     protected function predictSample(array $sample)
     {
         $predictions = [];
-        foreach ($this->labels as $index => $label) {
+        foreach ($this->targets as $index => $label) {
             $predictions[$label] = 0;
             foreach ($sample as $token => $count) {
                 if (array_key_exists($token, $this->samples[$index])) {
diff --git a/src/Phpml/Helper/Trainable.php b/src/Phpml/Helper/Trainable.php
index 36b8993..fda27d5 100644
--- a/src/Phpml/Helper/Trainable.php
+++ b/src/Phpml/Helper/Trainable.php
@@ -14,15 +14,15 @@ trait Trainable
     /**
      * @var array
      */
-    private $labels;
+    private $targets;
 
     /**
      * @param array $samples
-     * @param array $labels
+     * @param array $targets
      */
-    public function train(array $samples, array $labels)
+    public function train(array $samples, array $targets)
     {
         $this->samples = $samples;
-        $this->labels = $labels;
+        $this->targets = $targets;
     }
 }
diff --git a/src/Phpml/Pipeline.php b/src/Phpml/Pipeline.php
index 2ac0ed0..f0017fe 100644
--- a/src/Phpml/Pipeline.php
+++ b/src/Phpml/Pipeline.php
@@ -2,28 +2,85 @@
 
 declare (strict_types = 1);
 
-namespace Phpml\Pipeline;
+namespace Phpml;
 
-class Pipeline
+class Pipeline implements Estimator
 {
     /**
-     * @var array
+     * @var array|Transformer[]
      */
-    private $stages;
+    private $transformers;
 
     /**
-     * @param array $stages
+     * @var Estimator
      */
-    public function __construct(array $stages)
+    private $estimator;
+
+    /**
+     * @param array|Transformer[] $transformers
+     * @param Estimator $estimator
+     */
+    public function __construct(array $transformers = [], Estimator $estimator)
     {
-        $this->stages = $stages;
+        foreach ($transformers as $transformer) {
+            $this->addTransformer($transformer);
+        }
+
+        $this->estimator = $estimator;
     }
 
     /**
-     * @param mixed $stage
+     * @param Transformer $transformer
      */
-    public function addStage($stage)
+    public function addTransformer(Transformer $transformer)
     {
-        $this->stages[] = $stage;
+        $this->transformers[] = $transformer;
     }
+
+    /**
+     * @param Estimator $estimator
+     */
+    public function setEstimator(Estimator $estimator)
+    {
+        $this->estimator = $estimator;
+    }
+
+    /**
+     * @return array|Transformer[]
+     */
+    public function getTransformers()
+    {
+        return $this->transformers;
+    }
+
+    /**
+     * @return Estimator
+     */
+    public function getEstimator()
+    {
+        return $this->estimator;
+    }
+
+    /**
+     * @param array $samples
+     * @param array $targets
+     */
+    public function train(array $samples, array $targets)
+    {
+        foreach ($this->transformers as $transformer) {
+            $samples = $transformer->transform($samples);
+        }
+
+        $this->estimator->train($samples, $targets);
+    }
+
+    /**
+     * @param array $samples
+     * @return mixed
+     */
+    public function predict(array $samples)
+    {
+        return $this->estimator->predict($samples);
+    }
+
 }