public function testExceptionIsThrownInHashIterator()
 {
     $this->setExpectedException('DomainException', 'Callback exception');
     reject($this->hashIterator, [$this, 'exception']);
 }
<?php

use function Functional\true;
use function Functional\select;
use function Functional\reject;
use function Functional\false;
use Functional as F;
reject([1, 2, 3], 'callback');
false([true, true, true]);
$f = function () use($var) {
};