code: function mapValues(keys, app) {
    if (app.option('hints') === false || app.option('skip') === false) {
      return {ask: keys, skip: []};
    }
  
    var res = {ask: [], skip: []};
    for (var i = 0; i < keys.length; i++) {
      var key = keys[i];
      if (!app.has('cache.data', key)) {
        res.ask.push(key);
      } else {
        app.base.data(key, app.data(key));
        res.skip.push([key, app.data(key)]);
      }
    }
    return res;
  }
docs: Map values and filter out keys for data that has already been defined,
  to avoid asking unnecessary questions. This can be overridden
  with `--noskip`