# File lib/sass/script/functions.rb, line 1086
    def ie_hex_str(color)
      assert_type color, :Color, :color
      alpha = Sass::Util.round(color.alpha * 255).to_s(16).rjust(2, '0')
      identifier("##{alpha}#{color.send(:hex_str)[1..-1]}".upcase)
    end