    # File lib/compass/sass_extensions/functions/lists.rb, line 4
      def blank(obj)
        case obj
        when Sass::Script::Bool
          Sass::Script::Bool.new !obj.to_bool
        when Sass::Script::String
          Sass::Script::Bool.new obj.value.strip.size == 0
        when Sass::Script::List
          Sass::Script::Bool.new obj.value.size == 0 || obj.value.all?{|el| blank(el).to_bool}
        else
          Sass::Script::Bool.new false
        end
      end