Python: Human readable file size

size.py

def sizeof_fmt(num, iec=True):
    """Readable file size

    :param num: Bytes value
    :type num: int
    :param iec: default True, set iec pattern (powers of 1024),
            False set si pattern (powers of 1000)
    :type iec: boolean
    :rtype: str
    """
    ext_list = ['', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y']
    divisor = 1000.0
    if iec:
        ext_list = [item + 'i' for item in ext_list]
        divisor += 24.0
    for unit in ext_list:
        if abs(num) < divisor:
            break
        num /= divisor
    return "%.1f %sB" % (num, unit)