The proper way to do this is to define [`respond_to_missing?`](https://github.com/sqm/sqm_gator/blob/58ffcdd91ffa925307a07b343009948c5a0666d5/app/models/carrier.rb#L36-L38). More info on [this thoughtbot post](http://robots.thoughtbot.com/always-define-respond-to-missing-when-overriding).