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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 _accented_vowel_to_numbered(vowel):
 """Convert an accented Pinyin vowel to a numbered Pinyin vowel."""

    for numbered_vowel, accented_vowel in _PINYIN_TONES.items():
        if vowel == accented_vowel:
            return tuple(numbered_vowel)