code: def tokenize(s):
      
      s = re.sub(r'(?a)(\w+)\'s', r'\1', s) # clean the 's from Crohn's disease
      #s = re.sub(r'(?a)\b', ' ', s) # split the borders of chinese and english chars
  
      split_pattern = r'[{} ]+'.format(re.escape(STOPCHARS))
      tokens = [token for token in re.split(split_pattern, s) if not set(token) <= set(string.punctuation)]
      return tokens
docs: A simple tokneizer