Maybe you need to start a new version, or you just got tired of running it. 🤷

///

### Lifespan function

The first thing to notice, is that we are defining an async function with `yield`. This is very similar to Dependencies with `yield`.

{* ../../docs_src/events/tutorial003.py hl[14:19] *}

The first part of the function, before the `yield`, will be executed **before** the application starts.

   *
   * @param function A Function to transform the results of this future to the results of the
   *     returned future.
   * @param executor Executor to run the function in.
   * @return A future that holds result of the transformation.
   */
  public final <T extends @Nullable Object> FluentFuture<T> transform(
      Function<? super V, T> function, Executor executor) {

// and other runtime functions while identifying leaks.
var ignoredStackFns = []string{
	"",
	// Below are the stacks ignored by the upstream leaktest code.
	"testing.Main(",
	"testing.tRunner(",
	"testing.tRunner(",
	"runtime.goexit",
	"created by runtime.gc",
	// ignore the snapshot function.
	// since the snapshot is taken here the entry will have the current function too.

# Advanced Dependencies

## Parameterized dependencies

All the dependencies we have seen are a fixed function or class.

But there could be cases where you want to be able to set parameters on the dependency, without having to declare many different functions or classes.

Let's imagine that we want to have a dependency that checks if the query parameter `q` contains some fixed content.

But we want to be able to parameterize that fixed content.

	"net"
	"time"
)

// LookupHost is a function to make custom lookupHost for optional cached DNS requests
type LookupHost func(ctx context.Context, host string) (addrs []string, err error)

// DialContextWithLookupHost is a helper function which returns `net.DialContext` function.
// It randomly fetches an IP via custom LookupHost function and dials it by the given dial

	}
	// cleaning up the backend by removing all the directories and files created on function return.
	defer removeRoots(disks)

	// uses *testing.B and the object Layer to run the benchmark.
	runPutObjectPartBenchmark(b, objLayer, objSize)
}

// creates Erasure/FS backend setup, obtains the object layer and calls the runPutObjectBenchmark function.
func benchmarkPutObject(b *testing.B, instanceType string, objSize int) {

import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import com.google.common.base.Equivalence;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.common.collect.Ordering;
import com.google.common.primitives.UnsignedInteger;

# Request Parameters

Here's the reference information for the request parameters.

These are the special functions that you can put in *path operation function* parameters or dependency functions with `Annotated` to get data from the request.

It includes:

* `Query()`
* `Path()`
* `Body()`
* `Cookie()`
* `Header()`
* `Form()`
* `File()`

You can import them all directly from `fastapi`:

```python

and the called function begins execution.
The return parameters of the function are passed by value
back to the caller when the function returns.
</p>

<p>
Calling a <code>nil</code> function value
causes a <a href="#Run_time_panics">run-time panic</a>.
</p>

<p>
As a special case, if the return values of a function or method