StateConnecting

	// StateConnected is the state when the connection has been established and is considered stable.
	// If the connection is lost, state will switch to StateConnecting.
	StateConnected

	// StateConnectionError is the state once a connection attempt has been made, and it failed.
	// The connection will remain in this stat until the connection has been successfully re-established.
	StateConnectionError

- github.com/posener/complete: [v1.1.1](https://github.com/posener/complete/tree/v1.1.1)
- github.com/ryanuber/columnize: [9b3edd6](https://github.com/ryanuber/columnize/tree/9b3edd6)
- github.com/sean-/seed: [e2103e2](https://github.com/sean-/seed/tree/e2103e2)
- github.com/smartystreets/assertions: [b2de0cb](https://github.com/smartystreets/assertions/tree/b2de0cb)

    stack.addTearDown(tearDownOne);

    Callback callback =
        new Callback() {
          @Override
          public void run() {
            assertEquals(
                "tearDownTwo should have been run before tearDownOne", false, tearDownOne.ran);
          }
        };

    SimpleTearDown tearDownTwo = new SimpleTearDown(callback);
    stack.addTearDown(tearDownTwo);

    assertEquals(false, tearDownOne.ran);

 * Transformations can be applied at three different stages:
 * <ol>
 *   <li>File model - The raw model as read directly from the file</li>
 *   <li>Raw model - The model after inheritance has been applied</li>
 *   <li>Effective model - The fully processed model with all interpolation and inheritance applied</li>
 * </ol>
 * <p>
 * Implementations of this interface will be discovered through the Java ServiceLoader mechanism

    stack.addTearDown(tearDownOne);

    Callback callback =
        new Callback() {
          @Override
          public void run() {
            assertEquals(
                "tearDownTwo should have been run before tearDownOne", false, tearDownOne.ran);
          }
        };

    SimpleTearDown tearDownTwo = new SimpleTearDown(callback);
    stack.addTearDown(tearDownTwo);

    assertEquals(false, tearDownOne.ran);

   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
   * nullness analysis might not understand that the field has been populated. To avoid that problem
   * without having to add {@code @SuppressWarnings}, the code can call this method.
   *
   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is

    InterruptibleTask<?> localTask = task;
    if (localTask != null) {
      localTask.run();
    }
    /*
     * In the Async case, we may have called setFuture(pendingFuture), in which case afterDone()
     * won't have been called yet.
     */
    this.task = null;
  }

  @Override
  protected void afterDone() {
    super.afterDone();

    if (wasInterrupted()) {
      InterruptibleTask<?> localTask = task;

   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
   * nullness analysis might not understand that the field has been populated. To avoid that problem
   * without having to add {@code @SuppressWarnings}, the code can call this method.
   *
   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is

You can create production applications with **FastAPI** right now (and you have probably been doing it for some time), you just have to make sure that you use a version that works correctly with the rest of your code.

## Pin your `fastapi` version { #pin-your-fastapi-version }

But still, it is very powerful, and allows you to declare arbitrarily deeply nested dependency "graphs" (trees).

/// tip

All this might not seem as useful with these simple examples.

But you will see how useful it is in the chapters about **security**.

And you will also see the amounts of code it will save you.