class by appending the class name to guava.dev. For example,
[guava.dev/ImmutableList](https://guava.dev/ImmutableList)!

## Learn about Guava

-   Our users' guide, [Guava Explained]
-   [A nice collection](https://www.tfnico.com/presentations/google-guava) of
    other helpful links

## Links

-   [GitHub project](https://github.com/google/guava)

By default, **FastAPI** would automatically convert that return value to JSON using the `jsonable_encoder` explained in [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank}.

It will have a property `scopes` with a list containing all the scopes required by itself and all the dependencies that use this as a sub-dependency. That means, all the "dependants"... this might sound confusing, it is explained again later below.

The `security_scopes` object (of class `SecurityScopes`) also provides a `scope_str` attribute with a single string, containing those scopes separated by spaces (we are going to use it).

/// tip

For new code and whenever possible, use `Annotated` as explained above. There are multiple advantages (explained below) and no disadvantages. 🍰

///

This is how you would use `Query()` as the default value of your function parameter, setting the parameter `max_length` to 50:

Because of that, it's now recommended to instead use the `lifespan` as explained above.

## Technical Details { #technical-details }

Just a technical detail for the curious nerds. 🤓

   * method directly.
   *
   * <p>The returned object is serializable if {@code comparator} is serializable.
   *
   * <p><b>Java 8+ users:</b> this class is now obsolete as explained in the class documentation, so
   * there is no need to use this method.
   *
   * @param comparator the comparator that defines the order

 * which contained the following notice:
 *
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 * Other contributors include Andrew Wright, Jeffrey Hayes,
 * Pat Fisher, Mike Judd.
 */

package com.google.common.util.concurrent;

### Return a Response Directly { #return-a-response-directly }

The most common case would be [returning a Response directly as explained later in the advanced docs](../advanced/response-directly.md){.internal-link target=_blank}.

{* ../../docs_src/response_model/tutorial003_02_py39.py hl[8,10:11] *}

This is because by default, FastAPI will inspect every item inside and make sure it is serializable as JSON, using the same [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank} explained in the tutorial. This is what allows you to return **arbitrary objects**, for example database models.

/// tip

Review what each line does by clicking each number bubble in the code. 👆

///

/// warning

Make sure to **always** use the **exec form** of the `CMD` instruction, as explained below.

///

#### Use `CMD` - Exec Form { #use-cmd-exec-form }