) : SerialTask {
    override fun start() {
      taskRunner.assertThreadHoldsLock()
      require(currentTask == this)
      activeThreads++

      tasksExecutor.execute {
        taskRunner.assertThreadDoesntHoldLock()
        require(currentTask == this)
        try {
          runnable.run()
          require(currentTask == this) { "unexpected current task: $currentTask" }
        } finally {

## Privileges required

* Even dependencies can have dependencies, creating a hierarchy or **"graph" of dependencies**.
* All **automatically handled** by the framework.
* All the dependencies can require data from requests and **augment the path operation** constraints and automatic documentation.
* **Automatic validation** even for *path operation* parameters defined in dependencies.

functions with `Annotated` would **not be affected** at all.

If you call those functions in **other places in your code**, the actual **default values** will be kept, your editor will help you notice missing **required arguments**, Python will require you to pass required arguments at **runtime**, you will be able to **use the same functions** for different things and with different libraries (e.g. **Typer** will soon support `Annotated` too, then you could use the same function for an API...

            in diagnosticWithResolvedCallsAtPosition1 -> {
                require(diagnostic is DiagnosticWithParameters1<*, *>)
                @Suppress("UNCHECKED_CAST")
                diagnostic.a as Collection<ResolvedCall<*>>
            }
            in diagnosticWithResolvedCallsAtPosition2 -> {
                require(diagnostic is DiagnosticWithParameters2<*, *, *>)
                @Suppress("UNCHECKED_CAST")

      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each

to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the

[build-system]
requires = ["pdm-backend"]
build-backend = "pdm.backend"

[project]
name = "fastapi"
dynamic = ["version"]
description = "FastAPI framework, high performance, easy to learn, fast to code, ready for production"
readme = "README.md"
requires-python = ">=3.8"
authors = [
    { name = "Sebastián Ramírez", email = "******@****.***" },
]
classifiers = [
    "Intended Audience :: Information Technology",

    {!> ../../../docs_src/settings/app02/main.py!}
    ```

!!! tip
    We'll discuss the `@lru_cache` in a bit.

    For now you can assume `get_settings()` is a normal function.

And then we can require it from the *path operation function* as a dependency and use it anywhere we need it.

=== "Python 3.9+"

    ```Python hl_lines="17  19-21"
    {!> ../../../docs_src/settings/app02_an_py39/main.py!}
    ```

    * As the `q` parameter is declared with `= None`, it is optional.
    * Without the `None` it would be required (as is the body in the case with `PUT`).
* For `PUT` requests to `/items/{item_id}`, Read the body as JSON:
    * Check that it has a required attribute `name` that should be a `str`.
    * Check that it has a required attribute `price` that has to be a `float`.