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.

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])