def difference_update(self, *iterables):
_set = self._set<EOL>values = set(chain(*iterables))<EOL>if (<NUM_LIT:4> * len(values)) > len(_set):<EOL><INDENT>_list = self._list<EOL>_set.difference_update(values)<EOL>_list.clear()<EOL>_list.update(_set)<EOL><DEDENT>else:<EOL><INDENT>_discard = self.discard<EOL>for value in values:<EOL><INDENT>_discard(value)<EOL><DEDENT><DEDENT>return self<EOL>
Update the set, removing elements found in keeping only elements
found in any of the *iterables*.