def _from_python(self, key, value):
        new_path = self._path + (key,)
        if isinstance(value, dict):
            value = self.custom_classes.get(new_path, ConfigDict)(value, new_path)
        elif isinstance(value, list):
            value = self.custom_classes.get(new_path, ConfigList)(value, new_path)
        elif isinstance(value, str):
            match = self.PROXY_VAR_RE.match(value)
            if match:
                value = self._make_proxy(key, match)
        return value