How to use the @tanker/client-node.Tanker function in @tanker/client-node

async function main () {
  console.log(`Application: using Tanker version: ${Tanker.version}`);
  // Randomize emails so that each test runs with new users
  const aliceEmail = `alice-${uuid()}@example.com`;
  const bobEmail = `bob-${uuid()}@example.com`;

  // Init tanker
  console.log('Application: init Tanker object');
  const tankerConfig = await getTankerConfig();
  const tanker = new Tanker(tankerConfig);

  // Open Bob's session to make sure his account exists
  const bob = await signUp(bobEmail);
  console.log('Application: starting Tanker session for Bob');
  await tanker.start(bob.identity);
  await tanker.registerIdentity({ passphrase: 'Bob\'s secret passphrase'});
  await tanker.stop();
  console.log('Application: stopping Tanker session for Bob');

  // Open Alice's session
  const alice = await signUp(aliceEmail);
  console.log('Application: starting Tanker session for Alice');
  await tanker.start(alice.identity);
  await tanker.registerIdentity({ passphrase: 'Alice\'s secret passphrase' });

  console.log('Application: encrypting message for Bob');