# File lib/ranked-model/ranker.rb, line 33
      def validate_ranker_for_instance!
        if ranker.scope && !instance_class.respond_to?(ranker.scope)
          raise RankedModel::InvalidScope, %Q{No scope called "#{ranker.scope}" found in model}
        end

        if ranker.with_same
          if (case ranker.with_same
                when Symbol
                  !instance.respond_to?(ranker.with_same)
                when Array
                  array_element = ranker.with_same.detect {|attr| !instance.respond_to?(attr) }
                else
                  false
              end)
            raise RankedModel::InvalidField, %Q{No field called "#{array_element || ranker.with_same}" found in model}
          end
        end
      end