code: def format(self, record):
          
          out = dict(
              Timestamp=int(record.created * 1e9),
              Type=record.name,
              Logger=self.logger_name,
              Hostname=self.hostname,
              EnvVersion=self.LOGGING_FORMAT_VERSION,
              Severity=self.SYSLOG_LEVEL_MAP.get(record.levelno,
                                                 self.DEFAULT_SYSLOG_LEVEL),
              Pid=record.process,
          )
  
          # Include any custom attributes set on the record.
          # These would usually be collected metrics data.
          fields = dict()
          for key, value in record.__dict__.items():
              if key not in self.EXCLUDED_LOGRECORD_ATTRS:
                  fields[key] = value
  
          # Only include the 'message' key if it has useful content
          # and is not already a JSON blob.
          message = record.getMessage()
          if message:
              if not message.startswith("{") and not message.endswith("}"):
                  fields["msg"] = message
  
          # If there is an error, format it for nice output.
          if record.exc_info is not None:
              fields["error"] = repr(record.exc_info[1])
              fields["traceback"] = safer_format_traceback(*record.exc_info)
  
          out['Fields'] = fields
  
          return json.dumps(out)
docs: Map from Python LogRecord attributes to JSON log format fields
  
          * from - https://docs.python.org/3/library/logging.html#logrecord-attributes
          * to - https://mana.mozilla.org/wiki/pages/viewpage.action?pageId=42895640