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

By the last [Python Developer Survey](https://www.jetbrains.com/research/python-developers-survey-2018/#development-tools), that covers about 80% of the users.

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.

There were even some changes to Pydantic itself to support this.

The previous screenshots were taken with [Visual Studio Code](https://code.visualstudio.com).

But you would get the same editor support with [PyCharm](https://www.jetbrains.com/pycharm/) and most of the other Python editors:

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

/// tip

### Application Discovery { #application-discovery }

/// 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.

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 }

  fun cannotOperateOnEditAfterPublish() {
    val editor = cache.edit("k1")!!
    editor.setString(0, "A")
    editor.setString(1, "B")
    editor.commit()
    editor.assertInoperable()
  }

  @Test
  fun cannotOperateOnEditAfterRevert() {
    val editor = cache.edit("k1")!!
    editor.setString(0, "A")
    editor.setString(1, "B")
    editor.abort()
    editor.assertInoperable()
  }

  @Test

///

### Editor support { #editor-support }

All the framework was designed to be easy and intuitive to use, all the decisions were tested on multiple editors even before starting development, to ensure the best development experience.

{* ../../docs_src/response_status_code/tutorial002_py310.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.