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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def tokenize(s):
 """ A simple tokneizer """

    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