public function testOnce()
{
// from js + docs
$num = 0;
$increment = __u::once(function () use(&$num) {
return $num++;
});
$increment();
$increment();
$this->assertEquals(1, $num);
// extra
$num = 0;
$increment = __u(function () use(&$num) {
return $num++;
})->once();
$increment();
$increment();
$this->assertEquals(1, $num);
}