Method difference_update

test/perf/compiled_extensions.py:646–650

(self)

    @test_case
    def difference_update(self):
        ii = self.impl(self.val1)
        for _ in range(250):
            ii.difference_update(self.imp_2)
            ii.difference_update(self.val2)

    @test_case
    def isub(self):