def METHOD_NAME(self, before, after):
    arg_before = (sa.Identity(**before),) if before else ()
    arg_after = (sa.Identity(**after),) if after else ()
    m1 = MetaData()
    m2 = MetaData()
    Table(
        "user",
        m1,
        Column("id", Integer, *arg_before),
        Column("other", sa.Text),
    )
    Table(
        "user",
        m2,
        Column("id", Integer, *arg_after),
        Column("other", sa.Text),
    )
    diffs = self._fixture(m1, m2)
    eq_(len(diffs[0]), 1)
    diffs = diffs[0][0]
    eq_(diffs[0], "modify_default")
    eq_(diffs[2], "user")
    eq_(diffs[3], "id")
    old = diffs[5]
    new = diffs[6]
    def check(kw, idt):
        if kw:
            is_true(isinstance(idt, sa.Identity))
            for k, v in kw.items():
                eq_(getattr(idt, k), v)
        else:
            is_true(idt in (None, False))
    check(before, old)
    check(after, new)