Create new Base object and Collection is now extending it and final.

src/Base.php

@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace drupol\collection;
+
+use drupol\collection\Contract\Base as BaseInterface;
+use drupol\collection\Iterator\ClosureIterator;
+
+/**
+ * Class Base.
+ */
+abstract class Base implements BaseInterface
+{
+    /**
+     * @var \Closure
+     */
+    protected $source;
+
+    /**
+     * Base constructor.
+     *
+     * @param \Closure|iterable|mixed $data
+     */
+    public function __construct($data = [])
+    {
+        switch (true) {
+            case $data instanceof \Closure:
+                $this->source = $data;
+
+                break;
+            case \is_iterable($data):
+                $this->source = static function () use ($data) {
+                    foreach ($data as $k => $v) {
+                        yield $k => $v;
+                    }
+                };
+
+                break;
+
+            default:
+                $this->source = static function () use ($data) {
+                    foreach ((array) $data as $k => $v) {
+                        yield $k => $v;
+                    }
+                };
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getIterator(): ClosureIterator
+    {
+        return new ClosureIterator($this->source);
+    }
+
+    /**
+     * @param array $data
+     *
+     * @return \drupol\collection\Contract\Base
+     */
+    public static function with($data = []): BaseInterface
+    {
+        return new static($data);
+    }
+}