code: def add_fields(self, log_record, record, message_dict):
          
          for field in self._required_fields:
              log_record[field] = record.__dict__.get(field)
          log_record.update(message_dict)
          merge_record_extra(record, log_record, reserved=self._skip_fields)
  
          if self.timestamp:
              key = self.timestamp if type(self.timestamp) == str else 'timestamp'
              log_record[key] = datetime.utcnow()
docs: Override this method to implement custom logic for adding fields.