def METHOD_NAME(self):
    value = {"watson": {"language": "en", "alice": "bob"}, "foo": "bar"}
    actual = serialize.prefixed_collapsible_map(value, "Prefix")
    self.assertEqual(
        {
            "Prefix.watson.language": "en",
            "Prefix.watson.alice": "bob",
            "Prefix.foo": "bar",
        },
        actual,
    )