def after_check
      @checkers.each do |checker|
        after_check_callbacks = checker.class.get_callbacks(:after_check)
        after_check_callbacks.each do |block|
          checker.instance_exec &block
        end
      end
    end
def after_check
      @checkers.each do |checker|
        after_check_callbacks = checker.class.get_callbacks(:after_check)
        after_check_callbacks.each do |block|
          checker.instance_exec &block
        end
      end
    end
trigger all after_check callbacks defined in all checkers.