Low-level logging routine which creates a :class:`HistoryRecord`.

def _log(self, level, msg, args, exc_info=None, extra=None):
        """Low-level logging routine which creates a :class:`HistoryRecord`."""
        if exc_info and not isinstance(exc_info, tuple):
            exc_info = sys.exc_info()

        self.append(HistoryRecord(level, "unknown filename", 0, msg, args, exc_info, func="unknown func"))