Let's use the tools provided by **FastAPI** to handle security.

## How it looks

Let's first just use the code and see how it works, and then we'll come back to understand what's happening.

## Create `main.py`

Copy the example in a file `main.py`:

=== "Python 3.9+"

    ```Python
    {!> ../../../docs_src/security/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

      } finally {
        // Important to null this out here - if we did *not* execute inline, we might still
        // run() on the same thread that called execute() - such as in a thread pool, and think
        // that it was happening inline. As a side benefit, avoids holding on to the Thread object
        // longer than necessary.
        submitting = null;
      }
    }

    @SuppressWarnings("ShortCircuitBoolean")
    @Override

 * striped.get(key1) != striped.get(key2)}; the elements might nevertheless be mapped to the same
 * lock. The lower the number of stripes, the higher the probability of this happening.
 *
 * <p>There are three flavors of this class: {@code Striped<Lock>}, {@code Striped<Semaphore>}, and
 * {@code Striped<ReadWriteLock>}. For each type, two implementations are offered: {@linkplain

This idea of **asynchronous** code described above is also sometimes called **"concurrency"**. It is different from **"parallelism"**.

**Concurrency** and **parallelism** both relate to "different things happening more or less at the same time".

But the details between *concurrency* and *parallelism* are quite different.

To see the difference, imagine the following story about burgers:

### Concurrent Burgers

      assertThat(logged.get(0).getThrown()).isInstanceOf(MyException.class);
      assertThat(logged.get(1).getThrown()).isInstanceOf(MyException.class);
    }
  }

  /** The same exception happening on multiple futures should not be logged. */
  public void testAllAsList_logging_same_exception() throws Exception {
    try {
      MyException sameInstance = new MyException();

      assertThat(logged.get(0).getThrown()).isInstanceOf(MyException.class);
      assertThat(logged.get(1).getThrown()).isInstanceOf(MyException.class);
    }
  }

  /** The same exception happening on multiple futures should not be logged. */
  public void testAllAsList_logging_same_exception() throws Exception {
    try {
      MyException sameInstance = new MyException();

invited yet.'

  `You'll see me there,' said the Cat, and vanished.

  Alice was not much surprised at this, she was getting so used
to queer things happening.  While she was looking at the place
where it had been, it suddenly appeared again.

  `By-the-bye, what became of the baby?' said the Cat.  `I'd
nearly forgotten to ask.'

* Replace controller presence checking logic ([#36924](https://github.com/kubernetes/kubernetes/pull/36924), [@krousey](https://github.com/krousey))
* Fix a bug in scheduler happening after retrying unsuccessful bindings ([#37293](https://github.com/kubernetes/kubernetes/pull/37293), [@wojtek-t](https://github.com/wojtek-t))

false\n      return\n    }\n\n    const slideEvent = this._triggerSlideEvent(nextElement, eventDirectionName)\n    if (slideEvent.isDefaultPrevented()) {\n      return\n    }\n\n    if (!activeElement || !nextElement) {\n      // Some weirdness is happening, so we bail\n      return\n    }\n\n    this._isSliding = true\n\n    if (isCycling) {\n      this.pause()\n    }\n\n    this._setActiveIndicatorElement(nextElement)\n\n    const slidEvent = $.Event(Event.SLID, {\n      relatedTarget: nextElement,\n...

invited yet.'

  `You'll see me there,' said the Cat, and vanished.

  Alice was not much surprised at this, she was getting so used
to queer things happening.  While she was looking at the place
where it had been, it suddenly appeared again.

  `By-the-bye, what became of the baby?' said the Cat.  `I'd
nearly forgotten to ask.'