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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 get_sentences(self, root_element, block_tags):
 """Returns a list of plain-text sentences by iterating through XML tags except for those listed in block_tags."""

        sentences = []
        for element in root_element:
            if not self.any_ends_with(block_tags, element.tag):
                # tag not in block_tags
                if element.text is not None and not re.match('^\s*$',
                                                             element.text):
                    sentences.extend(self.sentence_tokenize(element.text))
                sentences.extend(self.get_sentences(element, block_tags))

        f = open('sentence_debug.txt', 'w')
        for s in sentences:
            f.write(s.lower() + '\n')
        f.close()
        return sentences