get the one element from 1-list or 1-set

[Skaperen]

i have a list or tuple or set or frozenset with exactly one element within. i'd like to code a simple way to get that one element that can be used with any of those container types. i can't use x[0] since that does not work with set or frozenset .

[Gribouillis]

next(iter(x)) perhaps?