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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 _find_solo_consonant(self, letters: List[str]) -> List[int]: """Find the positions of any solo consonants that are not yet paired with a vowel."""

        solos = []
        for idx, letter in enumerate(letters):
            if len(letter) == 1 and self._contains_consonants(letter):
                solos.append(idx)
        return solos