    # File lib/active_record/validations.rb, line 602
          def validates_inclusion_of(*attr_names)
            configuration = { :message => ActiveRecord::Errors.default_error_messages[:inclusion], :on => :save }
            configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

            enum = configuration[:in] || configuration[:within]

            raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?("include?")

            validates_each(attr_names, configuration) do |record, attr_name, value|
              record.errors.add(attr_name, configuration[:message]) unless enum.include?(value)
            end
          end