results.add(serializer.submit(Callables.returning(null), manualExecutor));
    Future<?>[] thingToCancel = new Future<?>[1];
    results.add(
        serializer.submit(
            () -> {
              thingToCancel[0].cancel(false);
              return null;
            },
            directExecutor()));
    thingToCancel[0] = serializer.submit(Callables.returning(null), directExecutor());

In this example, the function `generate_html_response()` already generates and returns a `Response` instead of returning the HTML in a `str`.

By returning the result of calling `generate_html_response()`, you are already returning a `Response` that will override the default **FastAPI** behavior.

// only sqlite, postgres, gaussdb, sqlserver support returning
func TestSoftDeleteReturning(t *testing.T) {
	if DB.Dialector.Name() != "sqlite" && DB.Dialector.Name() != "postgres" && DB.Dialector.Name() != "gaussdb" && DB.Dialector.Name() != "sqlserver" {
		return
	}

	users := []*User{
		GetUser("delete-returning-1", Config{}),
		GetUser("delete-returning-2", Config{}),
		GetUser("delete-returning-3", Config{}),
	}
	DB.Create(&users)

FastAPI will use this return type to:

* **Validate** the returned data.
    * If the data is invalid (e.g. you are missing a field), it means that *your* app code is broken, not returning what it should, and it will return a server error instead of returning incorrect data. This way you and your clients can be certain that they will receive the data and the data shape expected.
* Add a **JSON Schema** for the response, in the OpenAPI *path operation*.

	callbacks.RegisterDefaultCallbacks(db, &callbacks.Config{
		CreateClauses:        []string{"INSERT", "VALUES", "ON CONFLICT", "RETURNING"},
		UpdateClauses:        []string{"UPDATE", "SET", "WHERE", "RETURNING"},
		DeleteClauses:        []string{"DELETE", "FROM", "WHERE", "RETURNING"},
		LastInsertIDReversed: true,
	})

	return nil
}

func (DummyDialector) DefaultValueOf(field *schema.Field) clause.Expression {

You can also use it directly to create an instance of it and return it from your *path operations*.

Read more about it in the [FastAPI docs about returning a custom Response](https://fastapi.tiangolo.com/advanced/response-directly/#returning-a-custom-response)

You can import it directly from `fastapi`:

```python
from fastapi import Response
```

    results.add(serializer.submit(Callables.returning(null), manualExecutor));
    Future<?>[] thingToCancel = new Future<?>[1];
    results.add(
        serializer.submit(
            () -> {
              thingToCancel[0].cancel(false);
              return null;
            },
            directExecutor()));
    thingToCancel[0] = serializer.submit(Callables.returning(null), directExecutor());

                errors << "From non-null returning to null returning breaking change"
            } else if (oldNullability == Nullability.NON_NULL && newNullability == Nullability.UNMARKED) {
                errors << "From non-null returning to null-unmarked returning breaking change"
            } else if (oldNullability == Nullability.UNMARKED && newNullability == Nullability.NULLABLE) {

	}

	// mariadb with returning, values will be appended with id map
	if len(values) == beforeLen*2 {
		t.Skipf("This test case skipped, because the db supports returning")
	}

	for i := range values {
		v, ok := values[i]["id"]
		if !ok {
			t.Fatal("failed to create data from map with table, returning map has no primary key")
		}

		var result User

    assertFalse(task.isDone());
    task.run();
    assertTrue(task.isDone());
    assertFalse(task.isCancelled());
    assertEquals(2, getDone(task).intValue());
  }

  public void testCancelled() throws Exception {
    TrustedListenableFutureTask<Integer> task = TrustedListenableFutureTask.create(returning(2));
    assertFalse(task.isDone());
    task.cancel(false);