Activating a virtual environment also changes a couple of other things, but this is one of the most important things it does.

## Checking a Virtual Environment { #checking-a-virtual-environment }

When you check if a virtual environment is active, for example with:

//// tab | Linux, macOS, Windows Bash

```console
$ pip install "fastapi[standard]"

---> 100%
```

</div>

**Note**: Make sure you put `"fastapi[standard]"` in quotes to ensure it works in all terminals.

## Example { #example }

### Create it { #create-it }

Create a file `main.py` with:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")

You could also use it to generate code automatically, for clients that communicate with your API. For example, frontend, mobile or IoT applications.

## Recap, step by step { #recap-step-by-step }

### Step 1: import `FastAPI` { #step-1-import-fastapi }

{* ../../docs_src/first_steps/tutorial001.py hl[1] *}

MinIO versioning is designed to keep multiple versions of an object in one bucket. For example, you could store `spark.csv` (version `ede336f2`) and `spark.csv` (version `fae684da`) in a single bucket. Versioning protects you from unintended overwrites, deletions, protect objects with retention policies.

Así que, si creamos un objeto Pydantic `user_in` como:

```Python
user_in = UserIn(username="john", password="secret", email="john.doe@example.com")
```

y luego llamamos a:

```Python
user_dict = user_in.dict()
```

ahora tenemos un `dict` con los datos en la variable `user_dict` (es un `dict` en lugar de un objeto modelo Pydantic).

and it must not allow a single write to write multiple values.
</p>

<p>
All the following examples assume that `*p` and `*q` refer to
memory locations accessible to multiple goroutines.
</p>

<p>
Not introducing data races into race-free programs means not moving
writes out of conditional statements in which they appear.
For example, a compiler must not invert the conditional in this program:
</p>

<pre>
*p = 1

<address xmlns:hoge="http://www.example.com/hoge">
        <item sex="male" custid="A12345">
                <name>鈴木太郎</name>
                <access kind="email"></access>
                <access kind="url">http://www.taro.com/</access>
                <image file="taro.png" />
        </item>
        <item sex="male" custid="B23456">
                <name>佐藤二朗</name>
                <access kind="email">******@****.***</access>

📄 ❌ 🐕‍🦺:

* `allow_origins` - 📇 🇨🇳 👈 🔜 ✔ ⚒ ✖️-🇨🇳 📨. 🤶 Ⓜ. `['https://example.org', 'https://www.example.org']`. 👆 💪 ⚙️ `['*']` ✔ 🙆 🇨🇳.
* `allow_origin_regex` - 🎻 🎻 🏏 🛡 🇨🇳 👈 🔜 ✔ ⚒ ✖️-🇨🇳 📨. ✅ `'https://.*\.example\.org'`.
* `allow_methods` - 📇 🇺🇸🔍 👩‍🔬 👈 🔜 ✔ ✖️-🇨🇳 📨. 🔢 `['GET']`. 👆 💪 ⚙️ `['*']` ✔ 🌐 🐩 👩‍🔬.

* **`200 - 299`** are for "Successful" responses. These are the ones you would use the most.
    * `200` is the default status code, which means everything was "OK".
    * Another example would be `201`, "Created". It is commonly used after creating a new record in the database.

/// tip

📥 `tokenUrl="token"` 🔗 ⚖ 📛 `token` 👈 👥 🚫 ✍. ⚫️ ⚖ 📛, ⚫️ 🌓 `./token`.

↩️ 👥 ⚙️ ⚖ 📛, 🚥 👆 🛠️ 🔎 `https://example.com/`, ⤴️ ⚫️ 🔜 🔗 `https://example.com/token`. ✋️ 🚥 👆 🛠️ 🔎 `https://example.com/api/v1/`, ⤴️ ⚫️ 🔜 🔗 `https://example.com/api/v1/token`.

⚙️ ⚖ 📛 ⚠ ⚒ 💭 👆 🈸 🚧 👷 🏧 ⚙️ 💼 💖 [⛅ 🗳](../../advanced/behind-a-proxy.md){.internal-link target=_blank}.

///