langchain/experimental/generative_agents/memory.py/GenerativeAgentMemory/add_memory
class GenerativeAgentMemory:    def add_memory(
        self, memory_content: str, now: Optional[datetime] = None
    ) -> List[str]:
        """Add an observation or memory to the agent's memory."""
        importance_score = self._score_memory_importance(memory_content)
        self.aggregate_importance += importance_score
        document = Document(
            page_content=memory_content, metadata={"importance": importance_score}
        )
        result = self.memory_retriever.add_documents([document], current_time=now)

        # After an agent has processed a certain amount of memories (as measured by
        # aggregate importance), it is time to reflect on recent events to add
        # more synthesized memories to the agent's memory stream.
        if (
            self.reflection_threshold is not None
            and self.aggregate_importance > self.reflection_threshold
            and not self.reflecting
        ):
            self.reflecting = True
            self.pause_to_reflect(now=now)
            # Hack to clear the importance from reflection
            self.aggregate_importance = 0.0
            self.reflecting = False
        return result