langchain/tools/json/tool.py/JsonSpec/keys
class JsonSpec:    def keys(self, text: str) -> str:
        """Return the keys of the dict at the given path.

        Args:
            text: Python representation of the path to the dict (e.g. data["key1"][0]["key2"]).
        """
        try:
            items = _parse_input(text)
            val = self.dict_
            for i in items:
                if i:
                    val = val[i]
            if not isinstance(val, dict):
                raise ValueError(
                    f"Value at path `{text}` is not a dict, get the value directly."
                )
            return str(list(val.keys()))
        except Exception as e:
            return repr(e)