# File lib/sass/script/functions.rb, line 758
    def ie_hex_str(color)
      assert_type color, :Color
      alpha = (color.alpha * 255).round.to_s(16).rjust(2, '0')
      Sass::Script::String.new("##{alpha}#{color.send(:hex_str)[1..-1]}".upcase)
    end