The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.

* Each application that you have running on your computer has some process behind it, each running program, each window, etc. And there are normally many processes running **at the same time** while a computer is on.
* There can be **multiple processes** of the **same program** running at the same time.

                fun Int.invoke(some: Int) {}
                operator fun Boolean.invoke(some: Int) {}

                fun String.invoke(some: Int) {}
                operator fun Long.invoke(some: Int) {}

                fun Float.invoke(some: Int) {}
                infix fun Byte.invoke(some: Int) {}

                interface Source {
                    infix fun String.plus(some: List<Int>): String

</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.

    * A "token" is just a string with some content that we can use later to verify this user.
    * Normally, a token is set to expire after some time.
        * So, the user will have to log in again at some point later.
        * And if the token is stolen, the risk is less. It is not like a permanent key that will work forever (in most of the cases).

## Overriding dependencies during testing { #overriding-dependencies-during-testing }

There are some scenarios where you might want to override a dependency during testing.

You don't want the original dependency to run (nor any of the sub-dependencies it might have).

**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,...

https://github.com/google/guava/graphs/contributors. However, Git history
over-counts some people's contributions because they were responsible for
mirroring out changes from our internal repo.

This files serves mainly to credit people who have not received proper credit
in the Git history.

Doug Lea, author of some concurrency libraries

Joshua O'Madadhain (@jrtom), author of some common.graph commits beyond those

def test_route_converters_path():
    # Test path conversion
    response = client.get("/path/some/example")
    assert response.status_code == 200, response.text
    assert response.json() == {"path": "some/example"}


def test_route_converters_query():
    # Test query conversion
    response = client.get("/query", params={"param": "Qué tal!"})

                    public String[] baz() { return new String[] {"some"}; }
                }
            """,
            v2 = """
                public class Source {
                    @$nullUnmarkedAnnotationName public String foo() { return "bar"; }
                    public @$nullUnmarkedAnnotationName String[] baz() { return new String[] {"some", null}; }
                }
            """
        ) {