it can be seen in the home page (for people who don't know)

These are solutions, so only people who already solved this kata can see the comments. Why do I need to use a spoiler flag then?

Use a spoiler flag.

So what do you recommend, Ali?

Agree with Ali

...as mentioned already 3 times before...

this is not correct, since it is mutating the original list

Use method chaining. It will be much more faster cos JVM can optimize .append().append() calls.

6 people voted this as Best Practices…

True :-)

"""Do not mutate the original array/list."""