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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 indexableText(self, tree):
 """Provides the indexable - search engine oriented - raw text @param tree: an ElementTree """

        rval = set()
        root = tree.getroot()
        for txp in self.text_elts_xpaths:
            elts = txp(root)
            texts = []
            # Texts in element may be empty
            for elt in elts:
                text = self.text_extract_xpath(elt)
                if len(text) > 0:
                    texts.append(text[0])
            texts = self.separator.join(texts)
            texts = [toUnicode(x) for x in self.wordssearch_rx.findall(texts)
                     if len(x) > 0]
            rval |= set(texts)
        return rval