</div>

## Forbid Extra Headers { #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:

{* ../../docs_src/header_param_models/tutorial002_an_py310.py hl[10] *}

If a client tries to send some **extra headers**, they will receive an **error** response.

**projects depend on**. That's very difficult to manage. And you would probably end up running some projects with some **incompatible versions** of the packages, and not knowing why something isn't working.

Also, depending on your operating system (e.g. Linux, Windows, macOS), it could have come with Python already installed. And in that case it probably had some packages pre-installed with some specific versions **needed by your system**. If you install packages in the global Python environment,...

# Header

{* ../../docs_src/dependencies/tutorial013_an_py310.py ln[19:21] *}

Some text

{* ../../docs_src/bigger_applications/app_an_py310/internal/admin.py hl[3] title["app/internal/admin.py"] *}

Some more text

...

# Header 1 { #header-1 }

Some text with a link to [FastAPI](https://fastapi.tiangolo.com).

## Header 2 { #header-2 }

Two links here: [How to](https://fastapi.tiangolo.com/how-to/) and [Project Generators](project-generation.md){.internal-link target=_blank}.

### Header 3 { #header-3 }

Another link: [**FastAPI** Project Generators](project-generation.md "Link title"){.internal-link target=_blank} with title.

# Header 4 { #header-4 }

## Do not Separate Schemas { #do-not-separate-schemas }

Now, there are some cases where you might want to have the **same schema for input and output**.

Probably the main use case for this is if you already have some autogenerated client code/SDKs and you don't want to update all the autogenerated client code/SDKs yet, you probably will want to do it at some point, but maybe not right now.

	// Create a buffer to write our archive to.
	buf := new(bytes.Buffer)

	// Create a new zip archive.
	w := zip.NewWriter(buf)

	// Add some files to the archive.
	var files = []struct {
		Name, Body string
	}{
		{"readme.txt", "This archive contains some text files."},
		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
		{"todo.txt", "Get animal handling licence.\nWrite more examples."},
	}

# Header 1 { #header-1 }

Some text

# Header 2 { #header-2 }

Some more text

### Header 3 { #header-3 }

Even more text

# Header 4 { #header-4 }

A bit more text

#Not a header

# Advanced Security { #advanced-security }

## Additional Features { #additional-features }

There are some extra features to handle security apart from the ones covered in the [Tutorial - User Guide: Security](../../tutorial/security/index.md).

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first { #read-the-tutorial-first }

extend-exclude = [".git/", "docs/", "CREDITS", "go.mod", "go.sum"]
ignore-hidden = false

[default]
extend-ignore-re = [
    "Patrick Collison",
    "Copyright 2014 Unknwon",
    "[0-9A-Za-z/+=]{64}",
    "ZXJuZXQxDjAMBgNVBA-some-junk-Q4wDAYDVQQLEwVNaW5pbzEOMAwGA1UEAxMF",
    "eyJmb28iOiJiYXIifQ",
    "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.*",
    "MIIDBTCCAe2gAwIBAgIQWHw7h.*",
    'http\.Header\{"X-Amz-Server-Side-Encryptio":',

# Code blocks { #code-blocks }

Some text

```python
# This is a sample Python code block
def hello_world():
    # Comment with indentation
    print("Hello, world!")  # Print greeting
```

Some more text

The following block is missing first line:

```toml
title = "TOML Example"  # Title of the document
```

And more text

```console
// Use the command "live" and pass the language code as a CLI argument