How to use the epitran.ligaturize.ligaturize function in epitran

.format(self.g2p[source]))
                    target = source
                except IndexError:
                    logging.debug("self.g2p[source]={}".format(self.g2p[source]))
                    target = source
                tr_list.append((target, True))
                text = text[len(source):]
            else:
                tr_list.append((text[0], False))
                self.nils[text[0]] += 2
                text = text[1:]
        text = ''.join([s for (s, _) in filter(filter_func, tr_list)])
        if self.postproc:
            text = self.postprocessor.process(text)
        if ligatures or self.ligatures:
            text = ligaturize(text)
        if normpunc:
            text = self.puncnorm.norm(text)
        return unicodedata.normalize('NFC', text)

Args:
            text (unicode): English text
            normpunc (bool): if True, normalize punctuation downward
            ligatures (bool): if True, use non-standard ligatures instead of
                              standard IPA
        """
        text = unicodedata.normalize('NFC', text)
        acc = []
        for chunk in self.chunk_re.findall(text):
            if self.letter_re.match(chunk):
                acc.append(self.english_g2p(chunk))
            else:
                acc.append(chunk)
        text = ''.join(acc)
        text = self.puncnorm.norm(text) if normpunc else text
        text = ligaturize(text) if (ligatures or self.ligatures) else text
        return text

Returns:
            unicode: IPA string
        """
        tokens = self.cedict.tokenize(text)
        ipa_tokens = []
        for token in tokens:
            if token in self.cedict.hanzi:
                (pinyin, _) = self.cedict.hanzi[token]
                pinyin = u''.join(pinyin).lower()
                ipa = self.rules.apply(pinyin)
                ipa_tokens.append(ipa.replace(u',', u''))
            else:
                if normpunc:
                    token = self.normalize_punc(token)
                ipa_tokens.append(token)
            ipa_tokens = map(ligaturize, ipa_tokens)\
                if ligatures else ipa_tokens
        return u''.join(ipa_tokens)