docs: def find_extra(self, record):
          """Tries to find custom data from the old logging record.  The
          return value is a dictionary that is merged with the log record
          extra dictionaries.
          """
          rv = vars(record).copy()
          for key in ('name', 'msg', 'args', 'levelname', 'levelno',
                      'pathname', 'filename', 'module', 'exc_info',
                      'exc_text', 'lineno', 'funcName', 'created',
                      'msecs', 'relativeCreated', 'thread', 'threadName',
                      'processName', 'process'):
              rv.pop(key, None)
          return rv