def create(
        message: Optional[str],
        send_from: RoleName,
        send_to: RoleName = "Unknown",
        attachment_list: Optional[List[Attachment]] = None,
    ) -> Post:
        """create a post with the given message, send_from, send_to, and attachment_list."""
        return Post(
            id="post-" + create_id(),
            message=message is not None and message or "",
            send_from=send_from,
            send_to=send_to,
            attachment_list=attachment_list if attachment_list is not None else [],
        )
create a post with the given message, send_from, send_to, and attachment_list.
taskweaver/memory/post.py