def more(self):
        try:
            newsz = self.fsize()
        except __HOLE__:
            # file descriptor was closed
            return ''
        bytes_added = newsz - self.sz
        if bytes_added < 0:
            self.sz = 0
            return "==> File truncated <==\n"
        if bytes_added > 0:
            self.file.seek(-bytes_added, 2)
            bytes = self.file.read(bytes_added)
            self.sz = newsz
            return bytes
        return NOT_DONE_YET
dataset/ETHPy150Open XiaoMi/minos/supervisor/supervisor/http.py/tail_f_producer.more