code: def color_code(val)
        if val.is_a? String
          code = val
          val = code.hex
          val = -1 if val == 0 && code != '00'
        elsif val.is_a? Fixnum
          code = val
          val = val.to_i
          code = '%02x' % val
        else
          return nil
        end
  
        if (0..255).cover? val
          code
        else
          nil
        end
      end
docs: parse color code ("00" .. "ff")
   valid color-value is 0..255