* Tell me how you use FastAPI (I love to hear that).
    * Hear when I make announcements or release new tools.
    * You can also <a href="https://x.com/fastapi" class="external-link" target="_blank">follow @fastapi on X (Twitter)</a> (a separate account).
* <a href="https://www.linkedin.com/in/tiangolo/" class="external-link" target="_blank">Follow me on **LinkedIn**</a>.

    }
  }

  /**
   * Generates test cases for the given combination of scenario and timeouts. For methods that take
   * an explicit timeout value, all of the given timeoutsToUse result in individual test cases. For
   * methods that do not take an explicit timeout value, a single test case is generated only if the
   * implicit timeout of that method matches the given timeoutsToUse. For example, enter() is

Concurrency
===========

This document describes the concurrency considerations for http/2 connections and the connection pool within OkHttp.

## HTTP/2 Connections

The HttpURLConnection API is a blocking API. You make a blocking write to send a request, and a blocking read to receive the response.

#### Blocking APIs

      if (rule[0][0] == EXCEPTION_MARKER) {
        // Exception rules hold the effective TLD plus one.
        domainLabels.size - rule.size
      } else {
        // Otherwise the rule is for a public suffix, so we must take one more label.
        domainLabels.size - (rule.size + 1)
      }

    return splitDomain(domain).asSequence().drop(firstLabelOffset).joinToString(".")
  }

  private fun splitDomain(domain: String): List<String> {

            val delayNanos =
              logger.logElapsed(task, task.queue!!) {
                task.runOnce()
              }

            // A task ran successfully. Update the execution state and take the next task.
            task = withLock {
              afterRun(task, delayNanos, true)
              awaitTaskToRun()
            } ?: return
          }
        } catch (thrown: Throwable) {

 *     logger.info("Done with {0}", name);
 *   }
 * }, executor);
 * }
 *
 * <h3>How to get an instance</h3>
 *
 * <p>We encourage you to return {@code ListenableFuture} from your methods so that your users can
 * take advantage of the {@linkplain Futures utilities built atop the class}. The way that you will
 * create {@code ListenableFuture} instances depends on how you currently create {@code Future}
 * instances:
 *
 * <ul>

   * itself. In all other cases, the inverse is a transformation such that applying both the
   * original transformation and its inverse to a value gives you the original value give-or-take
   * numerical errors. Calling this method multiple times on the same instance will always return
   * the same instance. Calling this method on the result of calling this method on an instance will

When you install FastAPI, it comes with a production server, Uvicorn, and you can start it with the `fastapi run` command.

But you can also install an ASGI server manually.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then you can install the server application.

For example, to install Uvicorn:

<div class="termy">

```Python
{
    'username': 'john',
    'password': 'secret',
    'email': '******@****.***',
    'full_name': None,
}
```

#### Unpacking a `dict` { #unpacking-a-dict }

If we take a `dict` like `user_dict` and pass it to a function (or class) with `**user_dict`, Python will "unpack" it. It will pass the keys and values of the `user_dict` directly as key-value arguments.

{* ../../docs_src/body/tutorial001_py310.py hl[5:9] *}


The same as when declaring query parameters, when a model attribute has a default value, it is not required. Otherwise, it is required. Use `None` to make it just optional.

For example, this model above declares a JSON "`object`" (or Python `dict`) like:

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5