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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 _normalize_answer(text: str) -> str: """Lower text and remove punctuation, articles and extra whitespace."""


    parts = [_white_space_fix(_remove_articles(_normalize_number(_remove_punc(_lower(token)))))
             for token in _tokenize(text)]
    parts = [part for part in parts if part.strip()]
    normalized = ' '.join(parts).strip()
    return normalized