Matt Armstrong wrote:

>David Corbin <dcorbin / imperitek.com> writes:
>
>>I'm attempting to use this class
>>(http://www.hypermetrics.com/rubyset.html), and I don't see a way to
>>add individual elements to an existing Set.  I'm sure I'm missing
>>something, but even the tests don't reveal anything to me.
>>
>
>See the union! method.
>
>
def union!(other)
    @elts |= other.elts
    self
end

This says to me, novice that I am, that another Set is expected.