docs: function storeToken(token) {
    try {
      fs.mkdirSync(TOKEN_DIR);
    } catch (err) {
      if (err.code != 'EEXIST') {
        throw err;
      }
    }
    fs.writeFile(TOKEN_PATH, JSON.stringify(token), function(err) {
      if (err) throw err;
      console.log('Token stored to ' + TOKEN_PATH);
    });
  }