def open(filename=None, username=None):
    if filename is None:
        cmd = "crontab -l"
        if username:
            cmd += (username,) % " -u %s"
        ct = proctools.spawnpipe(cmd)
        text = ct.read()
        ct.close()
    else:
        text = open(filename).read()
    return CrontabFile(text, filename, username)
dataset/ETHPy150Open kdart/pycopia/process/pycopia/crontab.py/open/swapped operands of `%`