python 2.7 sets.Set update based on iterable method

sets.partial.py

    def _update(self, iterable):
        # The main loop for update() and the subclass __init__() methods.
        data = self._data

        # Use the fast update() method when a dictionary is available.
        if isinstance(iterable, BaseSet):
            data.update(iterable._data)
            return

        value = True

        if type(iterable) in (list, tuple, xrange):
            # Optimized: we know that __iter__() and next() can't
            # raise TypeError, so we can move 'try:' out of the loop.
            it = iter(iterable)
            while True:
                try:
                    for element in it:
                        data[element] = value
                    return
                except TypeError:
                    transform = getattr(element, "__as_immutable__", None)
                    if transform is None:
                        raise # re-raise the TypeError exception we caught
                    data[transform()] = value
        else:
            # Safe: only catch TypeError where intended
            for element in iterable:
                try:
                    data[element] = value
                except TypeError:
                    transform = getattr(element, "__as_immutable__", None)
                    if transform is None:
                        raise # re-raise the TypeError exception we caught
                    data[transform()] = value