langchain/cache.py/MomentoCache/__key
class MomentoCache:    def __key(self, prompt: str, llm_string: str) -> str:
        """Compute cache key from prompt and associated model and settings.

        Args:
            prompt (str): The prompt run through the language model.
            llm_string (str): The language model version and settings.

        Returns:
            str: The cache key.
        """
        return _hash(prompt + llm_string)