docs: function data(app, file, key) {
    var o = has(app.options, key);
    var c = has(app.cache.data, key);
    var d = has(file.data, key);
    if (!c && !d && !o) {
      set(file.data, key, comment(key, 'property'));
      console.log(warning(' missing variable:'));
    }
  }