/**
* @return mixed
*/
public function execute()
{
if ($this->collection instanceof PipelineInterface) {
$collection = $this->collection->execute();
if (!$collection instanceof CollectionInterface) {
throw new \UnexpectedValueException('Expecting an instance of ' . CollectionInterface::class);
}
} else {
$collection = $this->collection;
}
return call_user_func($this->callback, $collection);
}
