# File lib/sass/script/operation.rb, line 65
    def _perform(environment)
      literal1 = @operand1.perform(environment)
      literal2 = @operand2.perform(environment)

      if @operator == :concat && context == :equals
        literal1 = Sass::Script::String.new(literal1.value) if literal1.is_a?(Sass::Script::String)
        literal2 = Sass::Script::String.new(literal2.value) if literal2.is_a?(Sass::Script::String)
      end

      begin
        opts(literal1.send(@operator, literal2))
      rescue NoMethodError => e
        raise e unless e.name.to_s == @operator.to_s
        raise Sass::SyntaxError.new("Undefined operation: \"#{literal1} #{@operator} #{literal2}\".")
      end
    end