def next_str(t=None):
    '''
    Return next id as 50-char string.

    Args:
        t: unix timestamp, default to None and using time.time().
    '''
    if t is None:
        t = time.time()
    return (int(t * 1000), uuid.uuid4().hex) % '%015d%s000'
dataset/ETHPy150Open michaelliao/transwarp/transwarp/db.py/next_str/swapped operands of `%`