Getting first n unique elements from Python list

Question

I have a python list where elements can repeat.

>>> a = [1,2,2,3,3,4,5,6]

I want to get the first n unique elements from

Answer 1

Why not use something like this?

>>> a = [1, 2, 2, 3, 3, 4, 5, 6]
>>> list(set(a))[:5]
[1, 2, 3, 4, 5]