def validation(name=nil, options={}, &block)
      options = deprecate_validation_positional_args(name, options)
      name    = options[:name] # TODO: remove in favor of kw args in 3.0.

      heritage.record(:validation, options, &block)
      group = validation_groups.add(name, options)

      group.instance_exec(&block)
    end
def validation(name=nil, options={}, &block)
      options = deprecate_validation_positional_args(name, options)
      name    = options[:name] # TODO: remove in favor of kw args in 3.0.

      heritage.record(:validation, options, &block)
      group = validation_groups.add(name, options)

      group.instance_exec(&block)
    end
DSL.