With this, we get tooling support, from editors and mypy as this code is correct in terms of types, but we also get the data filtering from FastAPI.

How does this work? Let's check that out. 🤓

### Type Annotations and Tooling { #type-annotations-and-tooling }

First let's see how editors, mypy and other tools would see this.

I tested several ideas in the most popular Python editors: PyCharm, VS Code, Jedi based editors.

By the last <a href="https://www.jetbrains.com/research/python-developers-survey-2018/#development-tools" class="external-link" target="_blank">Python Developer Survey</a>, that covers about 80% of the users.

<img src="/img/tutorial/body/image05.png">

/// tip

If you use <a href="https://www.jetbrains.com/pycharm/" class="external-link" target="_blank">PyCharm</a> as your editor, you can use the <a href="https://github.com/koxudaxi/pydantic-pycharm-plugin/" class="external-link" target="_blank">Pydantic PyCharm Plugin</a>.

It improves editor support for Pydantic models, with:

* auto-completion

 *
 * <p>Strategies work with domtrip Documents for perfect formatting preservation.
 * Individual strategies can create domtrip Editors from Documents as needed:
 * <pre>
 * Editor editor = new Editor(document);
 * // ... perform domtrip operations ...
 * // Document is automatically updated
 * </pre>
 */
public interface UpgradeStrategy {

    /**

/// tip

Some editors check for unused function parameters, and show them as errors.

Using these `dependencies` in the *path operation decorator* you can make sure they are executed while avoiding editor/tooling errors.

 *
 * <p>This class recursively discovers all POM files in a Maven project hierarchy
 * and loads them as domtrip Documents. Individual strategies can create domtrip Editors
 * from these Documents as needed for superior formatting preservation.
 */
public class PomDiscovery {

    private PomDiscovery() {
        // noop
    }

    /**

 * and reduces code duplication across strategy implementations.
 *
 * <p>Strategies work with domtrip Documents for perfect formatting preservation.
 * Subclasses can create domtrip Editors from Documents as needed:
 * <pre>
 * Editor editor = new Editor(document);
 * // ... perform domtrip operations ...
 * // Document is automatically updated
 * </pre>
 */
public abstract class AbstractUpgradeStrategy implements UpgradeStrategy {

{* ../../docs_src/response_status_code/tutorial002_py39.py hl[1,6] *}

Diese sind nur eine Annehmlichkeit, sie enthalten dieselbe Zahl, aber so können Sie die Autovervollständigung Ihres Editors verwenden, um sie zu finden:

<img src="/img/tutorial/response-status-code/image02.png">

/// note | Technische Details

Sie könnten auch `from starlette import status` verwenden.

By doing that, your editor can provide support even while processing items from the list:

<img src="/img/python-types/image05.png">

Without types, that's almost impossible to achieve.

Notice that the variable `item` is one of the elements in the list `items`.

And still, the editor knows it is a `str`, and provides support for that.

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[9] *}

But then we get a `dict` in the parameter `commons` of the *path operation function*.

And we know that editors can't provide a lot of support (like completion) for `dict`s, because they can't know their keys and value types.

We can do better...

## What makes a dependency { #what-makes-a-dependency }