How to use the @reshadow/core.KEYS.__css__ function in @reshadow/core

parsed = parse(code, cacheKey, {
                elements,
                attributes,
                classes,
                onlyNamespaced,
                isMixin,
            });

            if (!isMixin) {
                __css__(parsed.css, cacheKey);
            }

            parsed.tokens = create([parsed.tokens].concat(mixinTokens));

            parsed.tokens[KEYS.__hash__] = cacheKey;
            parsed.tokens[KEYS.__css__] = parsed.css;

            cache[cacheKey] = parsed;
        }

        const tokens = Object.create(cache[cacheKey].tokens);

        tokens[KEYS.__style__] = Object.assign(vars, mixinVars);
        return tokens;
    }