callback_router0 = APIRouter()


@callback_router0.get("/")
async def callback0(level0: str):
    pass  # pragma: nocover


callback_router1 = APIRouter()


@callback_router1.get("/")
async def callback1(level1: str):
    pass  # pragma: nocover


callback_router2 = APIRouter()


@callback_router2.get("/")
async def callback2(level2: str):
    pass  # pragma: nocover


callback_router3 = APIRouter()

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: Annotated[CommonHeaders, Header()]):
    return headers
```

The non-blank variable names on the left side of <code>:=</code>
must be <a href="#Uniqueness_of_identifiers">unique</a>.
</p>

<pre>
field1, offset := nextField(str, 0)
field2, offset := nextField(str, offset)  // redeclares offset
x, y, x := 1, 2, 3                        // illegal: x repeated on left side of :=
</pre>

<p>
Short variable declarations may appear only inside functions.

  <mime-type type="application/x-ebu-stl">
    <acronym>EBU-STL</acronym>
    <_comment>EBU-STL subtitles</_comment>
    <tika:link>https://tech.ebu.ch/docs/tech/tech3264.pdf</tika:link>
    <magic priority="70">
      <match value="STL" type="string" offset="3">
        <match value=".01" type="string" offset="8" />
      </match>
    </magic>
    <!-- <glob pattern="*.stl"/> conflicts with 3D STL -->
  </mime-type>