If it finds it, then it will **use it**. Otherwise it keeps looking in the **other directories**.

### Installing Python and Updating the `PATH` { #installing-python-and-updating-the-path }

When you install Python, you might be asked if you want to update the `PATH` environment variable.

//// tab | Linux, macOS

Let's say you install Python and it ends up in a directory `/opt/custompython/bin`.

{* ../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py hl[10] *}

/// note

A path parameter is always required as it has to be part of the path. Even if you declared it with `None` or set a default value, it would not affect anything, it would still be always required.

///

## Order the parameters as you need { #order-the-parameters-as-you-need }

/// tip

    The only difference with a regular dependency is that it can declare OAuth2
    scopes that will be integrated with OpenAPI and the automatic UI docs (by default
    at `/docs`).

    It takes a single "dependable" callable (like a function).

    Don't call it directly, FastAPI will call it for you.

    Read more about it in the

It is quite an extensive specification and covers several complex use cases.

It includes ways to authenticate using a "third party".

That's what all the systems with "login with Facebook, Google, X (Twitter), GitHub" use underneath.

### OAuth 1 { #oauth-1 }

Deploying a **FastAPI** application is relatively easy.

## What Does Deployment Mean { #what-does-deployment-mean }

To **deploy** an application means to perform the necessary steps to make it **available to the users**.

For a **web API**, it normally involves putting it in a **remote machine**, with a **server program** that provides good performance, stability, etc, so that your **users** can **access** the application efficiently and without interruptions or problems.

            val (linesBeforeContributors, _, linesAfterContributors) = parseReleaseNotes()
            releaseNotes.asFile.get().writeText(
                "${linesBeforeContributors.joinToString("\n")}\n${sortedContributors.joinToString(",\n") { "[${it.value.name ?: it.key}](https://github.com/${it.key})" }}\n\n${linesAfterContributors.joinToString("\n")}\n"

        "it.unimi.dsi.fastutil.objects.Object2IntMap",
        "it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap",
        "it.unimi.dsi.fastutil.objects.Object2ObjectLinkedOpenHashMap",
        "it.unimi.dsi.fastutil.objects.Object2ObjectOpenCustomHashMap",
        "it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap",
        "it.unimi.dsi.fastutil.objects.ObjectOpenCustomHashSet",

```

///

* The `app` directory contains everything. And it has an empty file `app/__init__.py`, so it is a "Python package" (a collection of "Python modules"): `app`.
* It contains an `app/main.py` file. As it is inside a Python package (a directory with a file `__init__.py`), it is a "module" of that package: `app.main`.
* There's also an `app/dependencies.py` file, just like `app/main.py`, it is a "module": `app.dependencies`.

          stale-pr-label: stale
          stale-pr-message: >
            This pull request has been automatically marked as stale because it has not had recent activity.
            It will be closed in 14 days if no further activity occurs.
            If you don't want the stale bot to close it, then set a milestone for it.
          days-before-pr-close: 14
          close-pr-message: >

Then pass the parameter `deprecated=True` to `Query`:

{* ../../docs_src/query_params_str_validations/tutorial010_an_py310.py hl[19] *}

The docs will show it like this:

<img src="/img/tutorial/query-params-str-validations/image01.png">

## Exclude parameters from OpenAPI { #exclude-parameters-from-openapi }