# File lib/active_support/multibyte/unicode.rb, line 282
      def normalize(string, form=nil)
        form ||= @default_normalization_form
        # See http://www.unicode.org/reports/tr15, Table 1
        codepoints = u_unpack(string)
        case form
          when :d
            reorder_characters(decompose_codepoints(:canonical, codepoints))
          when :c
            compose_codepoints(reorder_characters(decompose_codepoints(:canonical, codepoints)))
          when :kd
            reorder_characters(decompose_codepoints(:compatability, codepoints))
          when :kc
            compose_codepoints(reorder_characters(decompose_codepoints(:compatability, codepoints)))
          else
            raise ArgumentError, "#{form} is not a valid normalization variant", caller
        end.pack('U*')
      end