add countable interface to eloquent factory sequence (#39907)

* add countable interface to eloquent factory sequence

* Update Sequence.php

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Database/Eloquent/Factories/Sequence.php

@@ -2,7 +2,9 @@
 
 namespace Illuminate\Database\Eloquent\Factories;
 
-class Sequence
+use Countable;
+
+class Sequence implements Countable
 {
     /**
      * The sequence of return values.
@@ -37,6 +39,16 @@ public function __construct(...$sequence)
         $this->count = count($sequence);
     }
 
+    /**
+     * Get the current count of the sequence items.
+     *
+     * @return int
+     */
+    public function count()
+    {
+        return $this->count;
+    }
+
     /**
      * Get the next value in the sequence.
      *