Illuminate\Support\Collection::flip PHP Method

    public function flip()
    {
        return new static(array_flip($this->items));
    }

 public function testFlip()
 {
     $data = new Collection(['name' => 'taylor', 'framework' => 'laravel']);
     $this->assertEquals(['taylor' => 'name', 'laravel' => 'framework'], $data->flip()->toArray());
 }