In RedisSet._update(), loop over appropriate thing (#68)
In RedisSet._update(), loop over appropriate thing (#68)

In Python, you can pass multiple iterables into `set.update()`.
Observe:

    >>> s = set()
    >>> s.update({1, 2}, {2, 3}, {3, 4})
    >>> s
    {1, 2, 3, 4}

Before, I was iterating over the iterables, then iterating over the
values of each iterable.  Simplify the logic by directly iterating over
the values of a chained iterable of iterables.
brainix/pottery