proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-NginX-Proxy true;

            # This is necessary to pass the correct IP to be hashed
            real_ip_header X-Real-IP;

            proxy_connect_timeout 300;
            
            # To support websocket
            proxy_http_version 1.1;

In our code example above, we don't use it directly, but we pass it to FastAPI for it to use it.

The `lifespan` parameter of the `FastAPI` app takes an **async context manager**, so we can pass our new `lifespan` async context manager to it.

{* ../../docs_src/events/tutorial003_py310.py hl[22] *}

            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-NginX-Proxy true;

            # This is necessary to pass the correct IP to be hashed
            real_ip_header X-Real-IP;

            proxy_connect_timeout 300;
            
            # To support websocket
            proxy_http_version 1.1;

- [ ] Write unit tests that match behavioral changes, where the tests fail if the changes to the runtime are not applied.
  This may not always be possible but is a best-practice.
- [ ] Run `mvn verify` to make sure basic checks pass.
  A more thorough check will be performed on your pull request automatically.
- [ ] You have run the [Core IT][core-its] successfully.

If your pull request is about ~20 lines of code you don't need to sign an

//
// passes NOATIME flag for reads on Unix systems to avoid atime updates.
func ReadFile(name string) ([]byte, error) {
	// Don't wrap with un-needed buffer.
	// Don't use os.ReadFile, since it doesn't pass NO_ATIME when present.
	f, err := OsOpenFile(name, readMode, 0o666)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	st, err := f.Stat()
	if err != nil {
		return io.ReadAll(f)
	}

{* ../../docs_src/dependencies/tutorial011_an_py310.py hl[12] *}

In this case, this `__call__` is what **FastAPI** will use to check for additional parameters and sub-dependencies, and this is what will be called to pass a value to the parameter in your *path operation function* later.

## Parameterize the instance { #parameterize-the-instance }

            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-NginX-Proxy true;

            # This is necessary to pass the correct IP to be hashed
            real_ip_header X-Real-IP;

            proxy_connect_timeout 300;
            
            # To support websocket
            proxy_http_version 1.1;

		if actualErr != nil && testCase.expectedError == nil {
			t.Errorf("Test %d: %s: Expected to pass, but failed with: error %s.", i, instanceType, actualErr.Error())
			continue
		}
		if actualErr == nil && testCase.expectedError != nil {

            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-NginX-Proxy true;

            # This is necessary to pass the correct IP to be hashed
            real_ip_header X-Real-IP;

            proxy_connect_timeout 300;
            
            # To support websocket
            proxy_http_version 1.1;

In that case, **FastAPI** also provides you with the tools to build it.

///

When we create an instance of the `OAuth2PasswordBearer` class we pass in the `tokenUrl` parameter. This parameter contains the URL that the client (the frontend running in the user's browser) will use to send the `username` and `password` in order to get a token.