setup!

# File activemodel/lib/active_model/validations/confirmation.rb, line 18
      def setup!(klass)
        klass.send(:attr_reader, *attributes.map do |attribute|
          :"#{attribute}_confirmation" unless klass.method_defined?(:"#{attribute}_confirmation")
        end.compact)

        klass.send(:attr_writer, *attributes.map do |attribute|
          :"#{attribute}_confirmation" unless klass.method_defined?(:"#{attribute}_confirmation=")
        end.compact)
      end