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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 normalizeIndex(value):
 """ Normalizes index. * **value** must be an ``int`` or ``None``. * Returned value is the same type as the input value. """

    if value is not None:
        if not isinstance(value, int):
            raise TypeError("Indexes must be None or integers, not %s."
                            % type(value).__name__)
    return value