How come set knows that it contains duplicate value and how it removes?

Question

Set contains unique key

Answer 1

I found this
https://stackoverflow.com/questions/15062322/how-sets-avoid-duplicates-internally

Answer 2

I think an exemplary implementation of a set is something like this
https://code.sololearn.com/c9hIiRK7XM1L/?ref=app

Answer 3

Thank you FD:)