How to run nightwatch.js tests in parallel?

I came across this question: How can I run multiple tests in parallel with JS/nightwatchjs?

But I want to execute multiple tests in parallel in the chrome browser only, in multiple chrome driver sessions.

I am used to java-testng-selenium based test suites where I can specify in the testng.xml file that I want to run multiple test classes or test methods in parallel and the framework does that exactly. If I specify in testng.xml that I want multiple test methods to execute in parallel in 4 threads, 4 chrome browser sessions pop-up and 4 test methods are executed in parallel.

Here's an example with a thread-count=2: https://github.com/adityai/testng-parallelsample/blob/master/methods-test-testng.xml

How can I do the same with nightwatch.js?