* **FastAPI**:
    * The same way that Starlette uses Uvicorn and cannot be faster than it, **FastAPI** uses Starlette, so it cannot be faster than it.

$ python main.py

Hello World from Python
```

</div>

!!! tip "Tipp"
    Weitere Informationen dazu finden Sie unter <a href="https://12factor.net/config" class="external-link" target="_blank">The Twelve-Factor App: Config</a>.

### Typen und Validierung

    It clearly inspired Uvicorn and Starlette, that are currently faster than Sanic in open benchmarks.

!!! check "Inspired **FastAPI** to"
    Find a way to have a crazy performance.

## What makes a dependency

Up to now you have seen dependencies declared as functions.

But that's not the only way to declare dependencies (although it would probably be the more common).

The key factor is that a dependency should be a "callable".

A "**callable**" in Python is anything that Python can "call" like a function.

// The env var no longer exists afterwards
$ python main.py

Hello World from Python
```

</div>

!!! tip
    You can read more about it at <a href="https://12factor.net/config" class="external-link" target="_blank">The Twelve-Factor App: Config</a>.

### Types and validation

Hello Wade Wilson from Python

// The env var no longer exists afterwards
$ python main.py

Hello World from Python
```

</div>

!!! tip
    👆 💪 ✍ 🌅 🔃 ⚫️ <a href="https://12factor.net/config" class="external-link" target="_blank">1️⃣2️⃣-⚖ 📱: 📁</a>.

### 🆎 &amp; 🔬

👫 🌐 🔢 💪 🕴 🍵 ✍ 🎻, 👫 🔢 🐍 &amp; ✔️ 🔗 ⏮️ 🎏 📋 &amp; 🎂 ⚙️ (&amp; ⏮️ 🎏 🏃‍♂ ⚙️, 💾, 🚪, 🇸🇻).

// 现在它可以读取环境变量

Hello Wade Wilson from Python

// 之后环境变量不再存在
$ python main.py

Hello World from Python
```

</div>

!!! tip
    您可以在 <a href="https://12factor.net/config" class="external-link" target="_blank">Twelve-Factor App: Config</a> 中阅读更多相关信息。

### 类型和验证

这些环境变量只能处理文本字符串，因为它们是外部于 Python 的，并且必须与其他程序和整个系统兼容（甚至与不同的操作系统，如 Linux、Windows、macOS）。

* ✅ Refactor 2 tests, for consistency and simplification. PR [#9504](https://github.com/tiangolo/fastapi/pull/9504) by [@tiangolo](https://github.com/tiangolo).
* ✅ Refactor OpenAPI tests, prepare for Pydantic v2. PR [#9503](https://github.com/tiangolo/fastapi/pull/9503) by [@tiangolo](https://github.com/tiangolo).

Import the `Response` class (sub-class) you want to use and declare it in the *path operation decorator*.

For large responses, returning a `Response` directly is much faster than returning a dictionary.

* **Machine Learning**: it normally requires lots of "matrix" and "vector" multiplications. Think of a huge spreadsheet with numbers and multiplying all of them together at the same time.