private function serializeList(PropertyList $list)
 {
     $serialization = [];
     foreach ($list->getElements() as $element) {
         $serialization[] = $this->serializeElement($element);
     }
     return $serialization;
 }
 public function testSetAndGetElements()
 {
     $items = [new PropertyListElement(new PropertyId('P1'), 'number', 'https://www.wikidata.org/wiki/Property:P1', 'http://api.queryr.com/properties/P1'), new PropertyListElement(new PropertyId('P2'), 'string', 'https://www.wikidata.org/wiki/Property:P2', 'http://api.queryr.com/properties/P2')];
     $list = new PropertyList($items);
     $this->assertSame($items, $list->getElements());
 }