`wsample(w)` behaves not as the documentation describes it

The doc says
> wsample([rng], [a], w)
> 
>   Select a weighted random sample of size 1 from a with probabilities
>   proportional to the weights given in w. If a is not present, **select a random**
>   **weight from w**.

From this, I expect `wsample(w) &isin; w`. However, I am getting

```julia
julia> wsample([1,10])
2
```