def run(string)
      string = string.to_s
      if ltr_mark?(string) && rtl_mark?(string)
        bidi
      elsif ltr_mark?(string)
        ltr
      elsif rtl_mark?(string)
        rtl
      end
    end
def run(string)
      string = string.to_s
      if ltr_mark?(string) && rtl_mark?(string)
        bidi
      elsif ltr_mark?(string)
        ltr
      elsif rtl_mark?(string)
        rtl
      end
    end
Look for the presence of unicode marks in given string and infers from them its direction

 params [String] The string to inspect
 @return [String, nil]