functionCall: FirFunctionCall,
        mode: KtConstantEvaluationMode,
    ): FirLiteralExpression<*>? {
        val function = functionCall.getOriginalFunction() as? FirSimpleFunction ?: return null

        val opr1 = evaluate(functionCall.explicitReceiver, mode) ?: return null
        opr1.evaluate(function)?.let {
            return it.adjustType(functionCall.resolvedType)
        }

        }

        // Preliminary extension function check
        val extensionCandidate = couldBeExtensionFunction && ktFunction.receiverTypeReference != null &&
            method.firstParameterMatches(ktFunction.receiverTypeReference!!) &&
            ktFunction.valueParameters.size == paramCountWithReceiver
        if (!(extensionCandidate || ktFunction.valueParameters.size == paramCount)) {

The [SliceAt(typ Type, p unsafe.Pointer, len int)] function
returns a Value representing a slice whose underlying array starts

```

### Advantages of `Annotated`

**Using `Annotated` is recommended** instead of the default value in function parameters, it is **better** for multiple reasons. 🤓

The **default** value of the **function parameter** is the **actual default** value, that's more intuitive with Python in general. 😌

                    // Stubbed top-level function IR symbols (from other source files in the module) require a parent facade class to be
                    // generated, which requires a container source to be provided. Without a facade class, function IR symbols will have
                    // an `IrExternalPackageFragment` parent, which trips up code generation during IR lowering.

Next, we create a custom subclass of `fastapi.routing.APIRoute` that will make use of the `GzipRequest`.

This time, it will overwrite the method `APIRoute.get_route_handler()`.

This method returns a function. And that function is what will receive a request and return a response.

Here we use it to create a `GzipRequest` from the original request.

```Python hl_lines="18-26"
{!../../../docs_src/custom_request_and_route/tutorial001.py!}

# Background Tasks - `BackgroundTasks`

You can declare a parameter in a *path operation function* or dependency function with the type `BackgroundTasks`, and then you can use it to schedule the execution of background tasks after the response is sent.

You can import it directly from `fastapi`:

```python
from fastapi import BackgroundTasks
```

### Custom Generate Unique ID Function

FastAPI uses a **unique ID** for each *path operation*, it is used for the **operation ID** and also for the names of any needed custom models, for requests or responses.

You can customize that function. It takes an `APIRoute` and outputs a string.

{!../../../docs_src/async_sql_databases/tutorial001.py!}
```

## Read notes

Create the *path operation function* to read notes:

```Python hl_lines="55-58"
{!../../../docs_src/async_sql_databases/tutorial001.py!}
```

!!! note
    Notice that as we communicate with the database using `await`, the *path operation function* is declared with `async`.

### Notice the `response_model=List[Note]`

It uses `typing.List`.

        closed over by local functions. Previously, such variables were
        sometimes incorrectly ignored.
    *   functions returned by the `get_concrete_function` method of
        `tf.function` objects can now be called with arguments consistent with
        the original arguments or type specs passed to `get_concrete_function`.
        This calling convention is now the preferred way to use concrete