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
    [FastAPI docs for Security](https://fastapi.tiangolo.com/tutorial/security/) and
    in the
    [FastAPI docs for OAuth2 scopes](https://fastapi.tiangolo.com/advanced/security/oauth2-scopes/).

If you need to enforce it, use `OAuth2PasswordRequestFormStrict` instead of `OAuth2PasswordRequestForm`.

///

* An optional `client_id` (we don't need it for our example).
* An optional `client_secret` (we don't need it for our example).

/// info

      stack.addFirst(closeable);
    }

    return closeable;
  }

  /**
   * Stores the given throwable and rethrows it. It will be rethrown as is if it is an {@code
   * IOException}, {@code RuntimeException} or {@code Error}. Otherwise, it will be rethrown wrapped
   * in a {@code RuntimeException}. <b>Note:</b> Be sure to declare all of the checked exception

            if (declared.contains(it) && computed.containsKey(it)) {
                null
            } else if (declared.contains(it)) {
                "Unnecessary declaration $it"
            } else {
                "Missing declaration $it via ${computed[it]}"
            }
        }.map { "   - $it" }
    }
}


private

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`.

```

///

* 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`.

* **FastAPI**:
    * The same way that Starlette uses Uvicorn and cannot be faster than it, **FastAPI** uses Starlette, so it cannot be faster than it.

For example, even though `users` would go after `items` in alphabetical order, it is shown before them, because we added their metadata as the first dictionary in the list.

## OpenAPI URL { #openapi-url }

By default, the OpenAPI schema is served at `/openapi.json`.

But you can configure it with the parameter `openapi_url`.

For example, to set it to be served at `/api/v1/openapi.json`:

{* ../../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

     * It should always return 0.
     */
    @Test
    void testWriteDataWireFormat() {
        byte[] dst = new byte[10];
        // The method should not write anything and return 0
        assertEquals(0, response.writeDataWireFormat(dst, 0), "writeDataWireFormat should return 0.");
    }

    /**
     * Test for the readSetupWireFormat method.
     * It should always return 0.
     */
    @Test