'Compiles and returns a regular expression for word tokenization'

def _word_tokenizer_re(self):

    try:
        return self._re_word_tokenizer
    except AttributeError:
        self._re_word_tokenizer = re.compile((self._word_tokenize_fmt % {u'NonWord': self._re_non_word_chars, u'MultiChar': self._re_multi_char_punct, u'WordStart': self._re_word_start}), (re.UNICODE | re.VERBOSE))
        return self._re_word_tokenizer
