langchain/experimental/generative_agents/memory.py/GenerativeAgentMemory/_get_memories_until_limit
class GenerativeAgentMemory:    def _get_memories_until_limit(self, consumed_tokens: int) -> str:
        """Reduce the number of tokens in the documents."""
        result = []
        for doc in self.memory_retriever.memory_stream[::-1]:
            if consumed_tokens >= self.max_tokens_limit:
                break
            consumed_tokens += self.llm.get_num_tokens(doc.page_content)
            if consumed_tokens < self.max_tokens_limit:
                result.append(doc)
        return self.format_memories_simple(result)