@bjori: Two changes for readability here. Line break before `is_numeric_array()`, so we can see the full conditional at a glance when scanning the code.

Also, a comment above the `if` explaining what's going on:

> If the first argument is an array of pipeline operators (i.e. numeric array), the second argument may be an options array and we can simply call `php_mongodb_aggregate()`. Otherwise, we'll disregard the zpp results and parse variable arguments below.