# File lib/sass/tree/mixin_def_node.rb, line 20
      def to_src(tabs, opts, fmt)
        args =
          if @args.empty?
            ""
          else
            '(' + @args.map do |v, d|
              if d
                "#{v.to_sass(opts)}: #{d.to_sass(opts)}"
              else
                v.to_sass(opts)
              end
            end.join(", ") + ')'
          end
              
        "#{'  ' * tabs}#{fmt == :sass ? '=' : '@mixin '}#{dasherize(@name, opts)}#{args}" +
          children_to_src(tabs, opts, fmt)
      end