group! (Builder::CSS)

    # File lib/active_support/vendor/builder-2.1.2/builder/css.rb, line 156
        def group!(*args, &block)
          args.each do |arg|
            if arg.is_a?(Symbol)
              instance_eval(&@library[arg])
            else
              instance_eval(&arg)
            end
            _text ', ' unless arg == args.last
          end
          if block
            _css_block(block)
            _unify_block
          end
        end