docs: def get_number(message, limit=4):
      """
      convert Chinese to pinyin and extract useful numbers
  
      attention:
          1. only for integer
          2. before apply this method, the message should be preprocessed
  
      input:
          message: the message you want to extract numbers from.
          limit: limit the length of number sequence
      """
      words = pinyin.get_pinyin(message).split('-')
      numbers = []
      tmp = ''
      count = 0
      for w in words:
          if re.search(r'\W', w, re.A):
              for s in list(w):
                  if s in special_char.keys():
                      count += 1
                      tmp += special_char[s]
                  else:
                      if count >= limit:
                          numbers.append(tmp)
                      count = 0
                      tmp = ''
          elif w in pinyin2number.keys():
              count += 1
              tmp += pinyin2number[w]
          else:
              if count >= limit:
                  numbers.append(tmp)
              count = 0
              tmp = ''
      if count >= limit:
          numbers.append(tmp)
      return numbers