This can make it a lot easier for your users to **implement their APIs** to receive your **webhook** requests, they might even be able to autogenerate some of their own API code.

/// info

Webhooks are available in OpenAPI 3.1.0 and above, supported by FastAPI `0.99.0` and above.

///

## An app with webhooks

Note that the go_darwin_$GOARCH_exec wrapper uninstalls any existing app identified by
the bundle id before installing a new app. If the uninstalled app is the last app by
the developer identity, the device might also remove the permission to run apps from
that developer, and the exec wrapper will fail to install the new app. To avoid that,
install another app with the same developer identity but with a different bundle id.

// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

TEXT errors(SB),$0
	MOV	$errors(SB), (X5)		// ERROR "address load must target register"
	MOV	$8(SP), (X5)			// ERROR "address load must target register"
	MOVB	$8(SP), X5			// ERROR "unsupported address load"
	MOVH	$8(SP), X5			// ERROR "unsupported address load"

/// tip

Some editors check for unused function parameters, and show them as errors.

Using these `dependencies` in the *path operation decorator* you can make sure they are executed while avoiding editor/tooling errors.

It might also help avoid confusion for new developers that see an unused parameter in your code and could think it's unnecessary.

///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package asm

import (
	"strings"
	"testing"

	"cmd/asm/internal/lex"
)

func tokenize(s string) [][]lex.Token {
	res := [][]lex.Token{}
	if len(s) == 0 {
		return res
	}
	for _, o := range strings.Split(s, ",") {
		res = append(res, lex.Tokenize(o))
	}

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// detect attempts to autodetect the correct
// values of the environment variables
// used by go_ios_exec.
// detect shells out to ideviceinfo, a third party program that can
// be obtained by following the instructions at
// https://github.com/libimobiledevice/libimobiledevice.

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Forbid Extra Headers

In some special use cases (probably not very common), you might want to **restrict** the headers that you want to receive.

You can use Pydantic's model configuration to `forbid` any `extra` fields:

//// tab | Python 3.10+

```Python hl_lines="10"

/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.

Licensed 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,

		err = drc[j].RouteConfig.UnmarshalTo(r)
		if err != nil {
			return false
		}
		return name < r.Name
	})

	// In Istio 1.5, it is not enough just to sort the routes.  The virtual hosts
	// within a route might have a different order.  Sort those too.
	for i := range drc {
		route := &route.RouteConfiguration{}
		err = drc[i].RouteConfig.UnmarshalTo(route)
		if err != nil {
			return nil, err
		}

    }

    /*
     * The ordering here is important: if we deleted the key entry and then the value entry,
     * the key entry's prev or next pointer might point to the dead value entry, and when we
     * put the new entry in the key entry's position in iteration order, it might invalidate
     * the linked list.
     */

    if (oldEntryForValue != null) {
      delete(oldEntryForValue);
    }