function testJoin()
 {
     $item1 = new lmbSet(array('x' => 'C'));
     $item2 = new lmbSet(array('x' => 'A'));
     $item3 = new lmbSet(array('x' => 'B'));
     $item4 = new lmbSet(array('x' => 'D'));
     $col1 = new lmbCollection(array($item1, $item2));
     $col2 = new lmbCollection(array($item3));
     $col3 = array($item4);
     $this->assertEqual($col1->join($col2)->join($col3), new lmbCollection(array($item1, $item2, $item3, $item4)));
 }