Documentation for method DELETE-POS, assembled from the following types:
multi method DELETE-POS (::?CLASS: )
Expected to delete the element at position
$index, and return the value it had. This is what
postcircumfix [ ] calls when invoked like
What "deleting" an element means, is up to your type.
Implementing this method is optional; if you don't, users trying to delete elements from an object of this type will get an appropriate error message.