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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 format_size(size, threshold=1536):
 """Return file size as string from byte size. '1234 B' '11.50 GiB' """

    if size < threshold:
        return "%i B" % size
    for unit in ('KiB', 'MiB', 'GiB', 'TiB', 'PiB'):
        size /= 1024.0
        if size < threshold:
            return "%.2f %s" % (size, unit)
    return 'ginormous'