beautify code, ajout méthode pluck et toArray à l'objet collection

src/Collection.php

@@ -57,8 +57,7 @@ class Collection implements IteratorAggregate, Countable
 
     public function map(callable $fn): Collection
     {
-        $tmp = array_map($fn, $this->elements);
-        return new Collection($tmp);
+        return new Collection(array_map($fn, $this->elements));
     }
 
     public function each(callable $fn): void
@@ -68,9 +67,24 @@ class Collection implements IteratorAggregate, Countable
 
     public function filter(callable $fn): Collection
     {
-        $tmp = array_filter($this->elements, $fn, ARRAY_FILTER_USE_BOTH);
-        $collect = new Collection($tmp);
-        return $collect;
+        return new Collection(array_filter($this->elements, $fn, ARRAY_FILTER_USE_BOTH));
+    }
+
+    public function pluck(string $key): Collection
+    {
+        return new Collection(array_map(function ($item) use ($key) {
+            if (is_object($item)) {
+                return isset($item->$key) ? $item->$key : null;
+            }
+            if (is_array($item)) {
+                return isset($item[$key]) ? $item[$key] : null;
+            }
+        }, $this->elements));
+    }
+
+    public function toArray(): array
+    {
+        return $this->elements;
     }
 
     public function empty(): bool