def freeze(self, skipSet = {}):
        if self._data is not None:
            if self.ignoreSkipSet or not skipSet:
                return self._data
            else:
                self._thaw()

        l = []
        for typeId, itemDict in sorted(self._items.iteritems()):
            itemList = sorted(itemDict)
            if itemList and not hasattr(itemList[0], '__cmp__'):
                raise AssertionError('Programming Error: %s type object '
                                     'does not have a __cmp__ method - '
                                     'sorting will be unstable'
                                     % itemList[0].__class__.__name__)

            for item in sorted(itemDict):
                s = item.freeze()
                if (1 << 16) >= len(s):
                    raise OverflowError
                l.append(pack.pack("!BSH", typeId, s))

        return "".join(l)
dataset/ETHPy150Open sassoftware/conary/conary/streams.py/StreamCollection.freeze/swapped operands of `>=`