Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="9"
    {!> ../../../docs_src/query_params_str_validations/tutorial006c.py!}
    ```

!!! tip

a.internal-link::after {
  /* \00A0 is a non-breaking space
        to make the mark be on the same line as the link
    */
  content: "\00A0↪";
}

.shadow {
  box-shadow: 5px 5px 10px #999;
}

/* Give space to lower icons so Gitter chat doesn't get on top of them */
.md-footer-meta {
  padding-bottom: 2em;
}

.user-list {
  display: flex;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}

.user-list-center {

* 🌐 Add French translation for FastAPI People. PR [#2232](https://github.com/tiangolo/fastapi/pull/2232) by [@JulianMaurin](https://github.com/JulianMaurin).
* 🌐 Add Korean translation for Tutorial - Path Parameters. PR [#2355](https://github.com/tiangolo/fastapi/pull/2355) by [@hard-coders](https://github.com/hard-coders).

## Top Translation Reviewers

These users are the **Top Translation Reviewers**. 🕵️

I only speak a few languages (and not very well 😅). So, the reviewers are the ones that have the [**power to approve translations**](contributing.md#translations){.internal-link target=_blank} of the documentation. Without them, there wouldn't be documentation in several other languages.

{% if people %}

If you are paying for 3 servers but you are using only a little bit of their RAM and CPU, you are probably **wasting money** 💸, and probably **wasting server electric power** 🌎, etc.

In that case, it could be better to have only 2 servers and use a higher percentage of their resources (CPU, memory, disk, network bandwidth, etc).

By declaring types for your variables, editors and tools can give you better support.

This is just a **quick tutorial / refresher** about Python type hints. It covers only the minimum necessary to use them with **FastAPI**... which is actually very little.

**FastAPI** is all based on these type hints, they give it many advantages and benefits.

👫 🐜 ✔️ 🧰 ⚒ 🔗 ⚖️ 🔗 🖖 🏓 ⚖️ 👨‍💼.

👉 🌌, 👆 💪 ✔️ 🔢 `orion_cat.owner` & 👨‍💼 🔜 🔌 💽 👉 🐶 👨‍💼, ✊ ⚪️➡️ 🏓 *👨‍💼*.

, `orion_cat.owner.name` 💪 📛 (⚪️➡️ `name` 🏓 `owners` 🏓) 👉 🐶 👨‍💼.

⚫️ 💪 ✔️ 💲 💖 `"Arquilian"`.

& 🐜 🔜 🌐 👷 🤚 ℹ ⚪️➡️ 🔗 🏓 *👨‍💼* 🕐❔ 👆 🔄 🔐 ⚫️ ⚪️➡️ 👆 🐶 🎚.

⚠ 🐜 🖼: ✳-🐜 (🍕 ✳ 🛠️), 🇸🇲 🐜 (🍕 🇸🇲, 🔬 🛠️) & 🏒 (🔬 🛠️), 👪 🎏.

    },
)
async def b():
    return "b"


@router.get(
    "/c",
    responses={
        "400": {"description": "Error with str"},
        "5xx": {"description": "Error with range, lower"},
        "default": {"description": "A default response"},
    },
)
async def c():
    return "c"


@router.get(
    "/d",
    responses={
        "400": {"description": "Error with str"},

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.

    class ModelC(ModelB):
        password: str

    class ModelA(BaseModel):
        name: str
        description: Optional[str] = None
        foo: ModelB

        @field_validator("name")
        def lower_username(cls, name: str, info: ValidationInfo):
            if not name.endswith("A"):
                raise ValueError("name must end in A")
            return name

    async def get_model_c() -> ModelC: