def METHOD_NAME(self) -> None:
    """Test format."""
    added = DictValue("k0", None, "value_0")
    self.assertEqual(added.changes(), [f"+{added.key} = {added.new_value}"])
    removed = DictValue("k1", "value_1", None)
    self.assertEqual(removed.changes(), [f"-{removed.key} = {removed.old_value}"])
    modified = DictValue("k2", "value_1", "value_2")
    self.assertEqual(
        modified.changes(),
        [
            f"-{modified.key} = {modified.old_value}",
            f"+{modified.key} = {modified.new_value}",
        ],
    )
    unmodified = DictValue("k3", "value_1", "value_1")
    self.assertEqual(
        unmodified.changes(), [f" {unmodified.key} = {unmodified.old_value}"]
    )
    self.assertEqual(
        unmodified.changes(), [f" {unmodified.key} = {unmodified.new_value}"]
    )