But before that, handling asynchronous code was quite more complex and difficult.

In previous versions of Python, you could have used threads or [Gevent](https://www.gevent.org/). But the code is way more complex to understand, debug, and think about.

* [**Swagger UI**](https://github.com/swagger-api/swagger-ui), with interactive exploration, call and test your API directly from the browser.

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-03-swagger-02.png)

* Alternative API documentation with [**ReDoc**](https://github.com/Rebilly/ReDoc).

# Handling Errors { #handling-errors }

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

inputParentClassOnError).removeClass(b.inputParentClassOnSuccess),""!==b.borderColorOnError&&a.css("border-color",b.borderColorOnError)},applyInputSuccessStyling:function(a,b){a.addClass(b.successElementClass),this.getParentContainer(a).addClass(b.inputParentClassOnSuccess)},removeInputStylingAndMessage:function(a,c){a.removeClass(c.successElementClass).removeClass(c.errorElementClass).css("border-color","");var d=b.getParentContainer(a);if(d.removeClass(c.inputParentClassOnError).removeClass(c....

        client.setChatResponse("{\"query\": \"broader search\", \"reasoning\": \"made broader\"}");

        final String result =
                client.regenerateQuery("specific question", "very specific query", "no_relevant_results", Collections.emptyList());

        assertEquals("broader search", result);

        // Verify the failure reason is in the prompt

			 <!--
			 "node.name":"search_engine",
			 "discovery.seed_hosts":"search_engine",
			 "cluster.initial_cluster_manager_nodes":"search_engine",
			 "node.roles":"cluster_manager,data,ingest,ml",
			 -->
			 "indices.breaker.total.limit":"100%",
			 "action.auto_create_index":"-*"}
		</property>
		<!-- Dictionaries -->
		<postConstruct name="addConfigFile">
			<arg>"fess"</arg>
			<arg>"mapping.txt"</arg>
		</postConstruct>

 * HttpURLConnections, for the complete JRE) to the same host with different or mixed anonymous/authenticated
 * credentials. Authenticated connections can/will be reused.
 *
 * @deprecated This is broken by design, even a possible vulnerability. Deprecation is conditional on whether future JDK
 *             versions will allow to do this safely.
 */
@Deprecated
public class NtlmHttpURLConnection extends HttpURLConnection {

Unfortunately, I can't simply trust PRs that just have several approvals.

Several times it has happened that there are PRs with 3, 5 or more approvals, probably because the description is appealing, but when I check the PRs, they are actually broken, have a bug, or don't solve the problem they claim to solve. 😅

So, it's really important that you actually read and run the code, and let me know in the comments that you did. 🤓

///

          return false;
        }
        i++;
      }
      return true;
    }

    @Override
    public boolean equals(@Nullable Object object) {
      // Warning: this is broken if size() == 0, so it is critical that we
      // substitute an empty ImmutableSet to the user in place of this
      if (object instanceof CartesianSet) {
        CartesianSet<?> that = (CartesianSet<?>) object;

        new CacheLoader<Object, Object>() {
          @Override
          public Object load(Object key) {
            return one;
          }

          @SuppressWarnings("CacheLoaderNull") // test of broken user implementation
          @Override
          public ListenableFuture<Object> reload(Object key, Object oldValue) {
            return null;
          }
        };