function hasCSSImport(files) {
  for (const file of files) {
    const code = fs.readFileSync(file, 'utf-8');
    const [imports] = parse(code);
    for (const {s, e} of imports.filter(({d}) => d === -1)) {
      const spec = code.substring(s, e);
      if (spec.endsWith('.css.proxy.js')) return true; // exit as soon as we find one
    }
  }
  return false;
}
Early-exit function that determines, given a set of JS files, if CSS is being imported