public function testImplementsCount()
 {
     $data = new Collection();
     $this->assertEquals(0, $data->count());
     $data->add('key', 'value');
     $this->assertEquals(1, count($data));
     $data->add('key', 'value2');
     $this->assertEquals(1, count($data));
     $data->add('key_2', 'value3');
     $this->assertEquals(2, count($data));
 }