Converting a list to a set changes element order

Question

Recently I noticed that when I am converting a list to set the order of elements is changed and is sorted by character.

Consider this examp

Answer 1

In Python 3.6, set() now should keep the order, but there is another solution for Python 2 and 3:

>>> x = [1, 2, 20, 6, 210]
>>> sorted(set(x), key=x.index)
[1, 2, 20, 6, 210]