///

## Write the callback documentation code { #write-the-callback-documentation-code }

This code won't be executed in your app, we only need it to *document* how that *external API* should look like.

But, you already know how to easily create automatic documentation for an API with **FastAPI**.

# Custom Docs UI Static Assets (Self-Hosting) { #custom-docs-ui-static-assets-self-hosting }

The API docs use **Swagger UI** and **ReDoc**, and each of those need some JavaScript and CSS files.

	}
	if err != nil {
		return 0
	}
	limit, err = strconv.ParseUint(strings.TrimSpace(string(buf)), 10, 64)
	if err != nil {
		// The kernel can return valid but non integer values
		// but still, no need to interpret more
		return 0
	}
	if limit >= 100*humanize.TiByte {
		// No limit set, or unreasonably high. Ignore
		return 0
	}
	return limit
}

func availableMemory() (available uint64) {

  /** Sorts the elements by their natural ordering. */
  /*
   * While the current implementation returns `this`, that's not something we mean to guarantee.
   * Callers of TestContainerGenerator.order need to be prepared for implementations to return a new
   * collection.
   */
  @SuppressWarnings("CanIgnoreReturnValueSuggester")
  @Override
  public List<String> order(List<String> insertionOrder) {

   * if Fire.run is called by delegate.addListener since addListener is called after the assignment
   * to timer, and importantly this is the main situation in which we need to be able to see the
   * write.
   *
   * 2. visibility of the writes to an afterDone() call triggered by cancel():
   *
   * Since these fields are non-final that means that TimeoutFuture is not being 'safely published',

//
// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
// large to fit in the [Scanner.Buffer]. When a scan stops, the reader may have
// advanced arbitrarily far past the last token. Programs that need more
// control over error handling or large tokens, or must run sequential scans
// on a reader, should use [bufio.Reader] instead.
type Scanner struct {
	r            io.Reader // The reader provided by the client.

     * This method is called automatically when using try-with-resources statements.
     *
     * <p>The default implementation does nothing. Subclasses should override this method
     * if they need to perform cleanup operations.</p>
     *
     * @throws InvokerException if an error occurs while closing the {@link Invoker}
     */
    @Override
    default void close() throws InvokerException {}

### Use cases: external service { #use-cases-external-service }

An example could be that you have an external authentication provider that you need to call.

You send it a token and it returns an authenticated user.

This provider might be charging you per request, and calling it might take some extra time than if you had a fixed mock user for tests.

* Add more granular permission controls with OAuth2 scopes where needed.
* ...etc.

Nevertheless, you might have a very specific use case where you really need to disable the API docs for some environment (e.g. for production) or depending on configurations from environment variables.

## Conditional OpenAPI from settings and env vars { #conditional-openapi-from-settings-and-env-vars }

This is not a limitation of **FastAPI**, it's part of the HTTP protocol.

///

## Recap { #recap }