# File lib/maruku/attributes.rb, line 7
    def to_s
      map do |k, v|
        value = quote_if_needed(v)
        case k
        when :id;    "#" + value
        when :class; "." + value
        when :ref;    value
        else quote_if_needed(k) + "=" + value
        end
      end.join(' ')
    end