def metadata
      {:definitions => representer_attrs.grep(Definition).map {|definition| definition.name},
       :links => representer_attrs.grep(Link).map {|link| link.options[:as] ? {link.rel => {'as' => link.options[:as]}} : link.rel}
      }
    end
def metadata
      {:definitions => representer_attrs.grep(Definition).map {|definition| definition.name},
       :links => representer_attrs.grep(Link).map {|link| link.options[:as] ? {link.rel => {'as' => link.options[:as]}} : link.rel}
      }
    end
represents the representer's schema in JSON format