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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(value, unit):
 """Converts the value so that it belongs to some expected range. Returns the new value and new unit. E.g: (1, 'MB') (1.5, 'hr') (1, 'object') """

    if value < 0:
        raise ValueError('Negative value: %s %s.' % (value, unit))

    if unit in functions.get_keys(INFORMATION_UNITS):
        return _normalize_information(value, unit)
    elif unit in TIME_UNITS:
        return _normalize_time(value, unit)
    else:
        # Unknown unit, just return it
        return functions.format_value(value), unit