# File lib/sass/tree/node.rb, line 396
      def children_to_src(tabs, opts, fmt)
        return fmt == :sass ? "\n" : " {}\n" if children.empty?

        (fmt == :sass ? "\n" : " {\n") +
          children.map {|c| c.send("to_#{fmt}", tabs + 1, opts)}.join.rstrip +
          (fmt == :sass ? "\n" : " }\n")
      end