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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_text(text: str) -> str: """ Performs a normalization that is very similar to that done by the normalization functions in SQuAD and TriviaQA. This involves splitting and rejoining the text, and could be a somewhat expensive operation. """

    return ' '.join([token
                     for token in text.lower().strip(STRIPPED_CHARACTERS).split()
                     if token not in IGNORED_TOKENS])