langchain/memory/chat_message_histories/firestore.py/FirestoreChatMessageHistory/__init__
class FirestoreChatMessageHistory:    def __init__(
        self,
        collection_name: str,
        session_id: str,
        user_id: str,
    ):
        """
        Initialize a new instance of the FirestoreChatMessageHistory class.

        :param collection_name: The name of the collection to use.
        :param session_id: The session ID for the chat..
        :param user_id: The user ID for the chat.
        """
        self.collection_name = collection_name
        self.session_id = session_id
        self.user_id = user_id

        self._document: Optional[DocumentReference] = None
        self.messages: List[BaseMessage] = []

        self.prepare_firestore()