langchain/memory/chat_message_histories/zep.py/ZepChatMessageHistory/add_message
class ZepChatMessageHistory:    def add_message(self, message: BaseMessage) -> None:
        """Append the message to the Zep memory history"""
        from zep_python import Memory, Message

        zep_message: Message
        if isinstance(message, HumanMessage):
            zep_message = Message(content=message.content, role="human")
        else:
            zep_message = Message(content=message.content, role="ai")

        zep_memory = Memory(messages=[zep_message])

        self.zep_client.add_memory(self.session_id, zep_memory)