Not quite. If I just put _call, Scheme will try to resolve the variable at compile-time. However, it hasn't been defined by then, so an error is thrown. In order to allow it to be defined in-Arc, I had to wrap it in a call to arc-eval.
I chose "call" because that's how "help" was named. The setters hash is just "setters," though, I believe. I dunno, if you come up with a better name, feel free to rename it.
I don't really care that much, (at least not enough to bother changing it), just thought we might want to follow pg's conventions (in so far as those conventions exist).