where() public method

Add a where clause ->where('x => x > 5')
public where ( $clause )
$clause
 public function testCollectionAcceptsArgumentAfterFiltering()
 {
     $collection = new Collection(array(new CollectionTestUser('jean-françois', 27, 500), new CollectionTestUser('bénédicte', 28, 500), new CollectionTestUser('bob', 5, 0), new CollectionTestUser('alice', 40, 0)));
     $request = $collection->where('user => user.age > 18 and user.age < 40');
     $collection->push(new CollectionTestUser('isAddedAfter', 30, 500));
     $this->assertEquals(3, sizeof($request));
 }