str_to_bytes

def bytes_to_str(size, mebi=False, precision=2):
    """Accept size in bytes, return size in string with KB, MB, GB
    Will always return, increase the fields with TB, etc to prevent
    103892GB or similar"""
    mult = 1024 if mebi else 1000
    units = {1000: ['KB', 'MB', 'GB'],
             1024: ['KiB', 'MiB', 'GiB']}
    for unit in units[mult]:
        size = size / mult
        if size < mult:
            break
    return '{}{}'.format(round(size, precision), unit)
def str_to_bytes(size):
    RE_SIZE = re.compile(r'^([\.\d]+)([a-z])(i)?b?$')
    parts = RE_SIZE.search(size.lower().replace(',', ''))
    if not parts:
        return int(size)
    size = parts.group(1)
    suffix = parts.group(2)
    mult = 1024 if parts.group(3) and "i" in parts.group(3) else 1000
    shift = int(suffix.translate(str.maketrans('kmgtp', '12345')))
    return int(float(size) * mult ** shift)