Why function template 'among' is of complexity O(1) and not O(n)?

[Tobias Pankrath]

On Wednesday, 19 February 2014 at 09:46:04 UTC, Gopan wrote:
> Index of 3 in (1,2,5,3) is 4
>
> Or, is my undertanding about Big-O notation of complexity wrong?
>
> Thanks,
> Gopan

O(1) = O(k) for any constant k.