docs: def to_digital(d, num):
      """
      进制转换，从10进制转到指定机制
      :param d:
      :param num:
      :return:
      """
      if not isinstance(num, int) or not 1 < num < 10:
          raise ValueError('digital num must between 1 and 10')
  
      d = int(d)
      result = []
      x = d % num
      d = d - x
      result.append(str(x))
      while d > 0:
          d = d // num
          x = d % num
          d = d - x
          result.append(str(x))
      return ''.join(result[::-1])