langchain/document_loaders/slack_directory.py/SlackDirectoryLoader/_get_message_metadata
class SlackDirectoryLoader:    def _get_message_metadata(self, message: dict, channel_name: str) -> dict:
        """Create and return metadata for a given message and channel."""
        timestamp = message.get("ts", "")
        user = message.get("user", "")
        source = self._get_message_source(channel_name, user, timestamp)
        return {
            "source": source,
            "channel": channel_name,
            "timestamp": timestamp,
            "user": user,
        }