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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 flag_dipthongs(self, syllables: List[str]) -> List[int]: """ Return a list of syllables that contain a dipthong :param syllables: :return: """

        long_positions = []
        for idx, syl in enumerate(syllables):
            for dipthong in self.constants.DIPTHONGS:
                if dipthong in syllables[idx]:
                    if not string_utils.starts_with_qu(syllables[idx]):
                        long_positions.append(idx)
        return long_positions