docs: function execute(storagePath, clientSecrets, executeAction) {
    const oauthClient = createOauthClient(storagePath, clientSecrets);
  
    // read existing credentials from token
    var existingToken = fs.readFileSync(path.join(storagePath, clientSecrets + '.token'));
    if (existingToken !== undefined) {
      oauthClient.credentials = JSON.parse(existingToken);
    } else {
      throw new Error('No existing authorization');
    }
    
    executeAction(oauthClient, google); 
  }