Minor changes here and there.

src/Operation/Until.php

@@ -21,25 +21,25 @@ final class Until implements Operation
     /**
      * Until constructor.
      *
-     * @param callable $until
+     * @param callable $callable
      */
-    public function __construct(callable $until)
+    public function __construct(callable $callable)
     {
-        $this->callable = $until;
+        $this->callable = $callable;
     }
 
     /**
      * {@inheritdoc}
      */
     public function on(iterable $collection): Closure
     {
-        $until = $this->callable;
+        $callable = $this->callable;
 
-        return static function () use ($until, $collection): Generator {
+        return static function () use ($callable, $collection): Generator {
             foreach ($collection as $key => $value) {
                 yield $key => $value;
 
-                if (true === $until($value, $key)) {
+                if (true === $callable($value, $key)) {
                     break;
                 }
             }

src/Transformation/Last.php

@@ -20,21 +20,12 @@ final class Last implements Transformation
      */
     public function on(iterable $collection)
     {
-        $iterator = new ClosureIterator(
-            static function () use ($collection): Generator {
-                foreach ($collection as $key => $value) {
-                    yield $key => $value;
-                }
-            }
-        );
+        $value = null;
 
-        $reduced = new Reduce(
-            static function ($carry, $item) {
-                return $item;
-            },
-            $iterator->current()
-        );
+        foreach ($collection as $key => $value) {
 
-        return $reduced->on($collection);
+        }
+
+        return $value;
     }
 }