def sizeof_fmt(num, suffix='B'):
    """ by Fred Cirera,  https://stackoverflow.com/a/1094933/1870254, modified"""
    for unit in ['', 'Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi']:
        if abs(num) < 1024.0:
            return '%3.1f %s%s' % (num, unit, suffix)
        num /= 1024.0
    return '%.1f %s%s' % (num, 'Yi', suffix)
