public function render()
{
$a = $this->getInlineArgument();
$b = $this->arguments['b'];
$aIsIterable = $this->assertIsArrayOrIterator($a);
if (true === $aIsIterable && null === $b) {
$a = $this->arrayFromArrayOrTraversableOrCSV($a);
return -array_sum($a);
}
return $this->calculate($a, $b);
}