in torchbeast/core/file_writer.py [0:0]
    def log(self, to_log: Dict, tick: int = None, verbose: bool = False) -> None:
        if tick is not None:
            raise NotImplementedError
        else:
            to_log["_tick"] = self._tick
            self._tick += 1
        to_log["_time"] = time.time()
        old_len = len(self.fieldnames)
        for k in to_log:
            if k not in self.fieldnames:
                self.fieldnames.append(k)
        if old_len != len(self.fieldnames):
            self._fieldwriter.writerow(self.fieldnames)
            self._logger.info("Updated log fields: %s", self.fieldnames)
        if to_log["_tick"] == 0:
            self._logfile.write("# %s\n" % ",".join(self.fieldnames))
        if verbose:
            self._logger.info(
                "LOG | %s",
                ", ".join(["{}: {}".format(k, to_log[k]) for k in sorted(to_log)]),
            )
        self._logwriter.writerow(to_log)
        self._logfile.flush()