# File lib/sass/tree/variable_node.rb, line 28
      def _perform(environment)
        return [] if @guarded && !environment.var(@name).nil?
        val = @expr.perform(environment)
        if @expr.context == :equals && val.is_a?(Sass::Script::String)
          val = Sass::Script::String.new(val.value)
        end
        environment.set_var(@name, val)
        []
      end