How do I limit the number of results provided by [Stack.PHP](https://stackapps.com/q/826) (a library wrapper over the Stackexchange API)?

For example, how do I get the first 50 questions tagged with a keyword?

The query I currently have is:

    $apps = $stackapps->Questions()->Tagged('drupal')->IncludeAnswers()->IncludeBody()->Exec();