Function plugin

test/loader.test.js:115–119

* @returns {(style: EXPECTED_ANY) => void} stylus plugin

()

     * @returns {(style: EXPECTED_ANY) => void} stylus plugin
     */
    function plugin() {
      return (style) => {
        style.define("add", (a, b) => a.operate("+", b));
      };
    }

    const testId = "./webpack.config-plugin.styl";
    const compiler = getCompiler(testId, {