code: function updateAccount() {
  
    account.middleName = 'Make it so.';
  
    return account.save(function(err, savedAccount) {
      if (err) throw err;
      account = savedAccount;
      console.log('Updated account:');
      console.log(account);
      return authenticateAccount(); //next quickstart step
    });
  
  }
docs: ================================================== Step 3 - Update an account ==================================================