///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md){.internal-link target=_blank}.

///

## Dependencies errors and return values

You can use the same dependency *functions* you use normally.

### Dependency requirements

        try {
          Event nextEvent;
          while ((nextEvent = queueForThread.poll()) != null) {
            while (nextEvent.subscribers.hasNext()) {
              nextEvent.subscribers.next().dispatchEvent(nextEvent.event);
            }
          }
        } finally {
          dispatching.remove();
          queue.remove();
        }
      }
    }

        printErrors(result);

        Iterator<Artifact> i = result.getArtifacts().iterator();
        assertEquals(n, i.next(), "n should be first");
        assertEquals(m, i.next(), "m should be second");

        // inverse order
        set = new LinkedHashSet<>();
        set.add(m);
        set.add(n);

 * acquire(1000)} will result in exactly the same throttling, if any), but it affects the throttling
 * of the <i>next</i> request. I.e., if an expensive task arrives at an idle RateLimiter, it will be
 * granted immediately, but it is the <i>next</i> request that will experience extra throttling,
 * thus paying for the cost of the expensive task.
 *
 * @author Dimitris Andreou
 * @since 13.0
 */

I'll show you some concrete examples in the next chapters.

---

Then the next concepts to consider are all about the program running your actual API (e.g. Uvicorn).

## Program and Process

     */
    void add(Problem.Severity severity, String message, int line, int column, Exception cause);

    /**
     * The next messages will be bound to this source. When calling this method again, previous messages keep
     * their source, but the next messages will use the new source.
     *
     * @param source a source
     */
    void setSource(String source);

    /**
     *

## Integrated middlewares

**FastAPI** includes several middlewares for common use cases, we'll see next how to use them.

/// note | "Technical Details"

For the next examples, you could also use `from starlette.middleware.something import SomethingMiddleware`.

      StringBuilder sb = new StringBuilder();
      Iterator<String> iterator = components.iterator();
      if (iterator.hasNext()) {
        sb.append(iterator.next().toString());
        while (iterator.hasNext()) {
          sb.append(DELIMITER_STRING);
          sb.append(iterator.next());
        }
      }
      dummy ^= sb.toString().length();
    }
    return dummy;
  }

  /**

        @Override
        public boolean hasNext() {
          return backingEntries.hasNext();
        }

        @Override
        public Multiset.Entry<E> next() {
          final Map.Entry<E, Integer> mapEntry = backingEntries.next();
          return new Multisets.AbstractEntry<E>() {
            @Override
            public E getElement() {
              return mapEntry.getKey();
            }

				b.RunParallel(func(pb *testing.PB) {
					rng := rand.New(rand.NewSource(time.Now().UnixNano()))
					n := 0
					var latency int64
					managers := grid.Managers
					hosts := grid.Hosts
					for pb.Next() {
						// Pick a random manager.
						src, dst := rng.Intn(len(managers)), rng.Intn(len(managers))
						if src == dst {
							dst = (dst + 1) % len(managers)
						}
						local := managers[src]