public function testCompact()
 {
     $vals = array(0, 1, false, 2, false, 3);
     // from js
     $this->assertEquals(3, count(__u::compact($vals)), 'can trim out all falsy values');
     $func = function () {
         return count(__u(func_get_args())->compact());
     };
     $result = $func(0, 1, false, 2, false, 3);
     $this->assertEquals(3, $result, 'works on arguments');
     // extra
     $this->assertEquals(array(1, 2, 3), __u::compact($vals), 'can remove all falsy values');
     // docs
     $this->assertEquals(array(true, 'a', 1), __u::compact(array(false, true, 'a', 0, 1, '')));
 }