langchain/chains/moderation.py/OpenAIModerationChain/_call
class OpenAIModerationChain:    def _call(
        self,
        inputs: Dict[str, str],
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Dict[str, str]:
        text = inputs[self.input_key]
        results = self.client.create(text)
        output = self._moderate(text, results["results"][0])
        return {self.output_key: output}