# File lib/active_support/rescuable.rb, line 44
      def rescue_from(*klasses, &block)
        options = klasses.extract_options!

        unless options.has_key?(:with)
          if block_given?
            options[:with] = block
          else
            raise ArgumentError, "Need a handler. Supply an options hash that has a :with key as the last argument."
          end
        end

        klasses.each do |klass|
          key = if klass.is_a?(Class) && klass <= Exception
            klass.name
          elsif klass.is_a?(String)
            klass
          else
            raise ArgumentError, "#{klass} is neither an Exception nor a String"
          end

          # put the new handler at the end because the list is read in reverse
          rescue_handlers << [key, options[:with]]
        end
      end