find_nth_from_last

# File activerecord/lib/active_record/relation/finder_methods.rb, line 543
      def find_nth_from_last(index)
        if loaded?
          records[-index]
        else
          relation = if order_values.empty? && primary_key
            order(arel_attribute(primary_key).asc)
          else
            self
          end

          relation.to_a[-index]
          # TODO: can be made more performant on large result sets by
          # for instance, last(index)[-index] (which would require
          # refactoring the last(n) finder method to make test suite pass),
          # or by using a combination of reverse_order, limit, and offset,
          # e.g., reverse_order.offset(index-1).first
        end
      end