the start of the function <code>main.main</code>.
</p>

<h3 id="go">Goroutine creation</h3>

<p class="rule">
The <code>go</code> statement that starts a new goroutine
is synchronized before the start of the goroutine's execution.
</p>

<p>
For example, in this program:
</p>

<pre>
var a string

func f() {
	print(a)
}

```

## `APIRouter`

Vamos supor que o arquivo dedicado a lidar apenas com usuários seja o submódulo em `/app/routers/users.py`.

Você quer manter as *operações de rota* relacionadas aos seus usuários separadas do restante do código, para mantê-lo organizado.

Mas ele ainda faz parte da mesma aplicação/web API **FastAPI** (faz parte do mesmo "pacote Python").

Você pode criar as *operações de rotas* para esse módulo usando o `APIRouter`.

  TFE_TensorHandle* h2 = TestVariable(ctx, 3.0, task0_name);

  // Add a sync point to make sure that variables have been initialized
  // before the function execution starts.
  TFE_ContextAsyncWait(ctx, status);
  EXPECT_EQ(TF_OK, TF_GetCode(status)) << TF_Message(status);

  // Pack 3 variable handles into one TFE_TensorHandle.

 *  New: `Response.byteString()` reads the entire response into memory as a byte string.
 *  New: `OkHttpClient.x509TrustManager` accessor.
 *  New: Permit [new WebSocket response codes][iana_websocket]: 1012 (Service Restart), 1013 (Try
    Again Later), and 1014 (invalid response from the upstream).
 *  New: Build with Kotlin 1.3.41, BouncyCastle 1.62, and Conscrypt 2.2.1.

   * time a task is submitted.
   *
   * <p>When an {@code Error} is thrown by an executed task, previously submitted tasks may never
   * run. An attempt will be made to restart execution on the next call to {@code execute}. If the
   * {@code delegate} has begun to reject execution, the previously submitted tasks may never run,

- Selector or node used as arrow */\n    element: '[x-arrow]',\n  },\n\n  /**\n   * Modifier used to flip the popper's placement when it starts to overlap its\n   * reference element.\n   *\n   * Requires the `preventOverflow` modifier before it in order to work.\n   *\n   * **NOTE:** this modifier will interrupt the current update cycle and will\n   * restart it if it detects the need to flip the placement.\n   * @memberof modifiers\n   * @inner\n   */\n  flip: {\n    /** @prop {number} order=600...

///

```Python hl_lines="11"
{!> ../../docs_src/query_params_str_validations/tutorial004.py!}
```

////

This specific regular expression pattern checks that the received parameter value:

* `^`: starts with the following characters, doesn't have characters before.
* `fixedquery`: has the exact value `fixedquery`.
* `$`: ends there, doesn't have any more characters after `fixedquery`.

      next = (keyList == null) ? null : keyList.head;
    }

    /**
     * Constructs a new iterator over all values for the specified key starting at the specified
     * index. This constructor is optimized so that it starts at either the head or the tail,
     * depending on which is closer to the specified index. This allows adds to the tail to be done
     * in constant time.
     *
     * @throws IndexOutOfBoundsException if index is invalid

      MoreFiles.deleteRecursively(symlink);

      assertFalse(Files.exists(symlink, NOFOLLOW_LINKS));
      assertTrue(Files.isDirectory(realSymlinkTarget, NOFOLLOW_LINKS));
    }
  }

  /**
   * Starts a new task on the given executor that switches (deletes and replaces) a file between
   * being a directory and being a symlink. The given {@code file} is the file that should switch

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[25:30]  hl[25:27,30] *}

### Create Database Tables on Startup

We will create the database tables when the application starts.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[32:37] hl[35:37] *}

Here we create the tables on an application startup event.