### Otras funciones de utilidad { #other-utility-functions }

Cualquier otra función de utilidad que llames directamente puede ser creada con `def` normal o `async def` y FastAPI no afectará la forma en que la llames.

@Deprecated(since = "4.0.0")
public interface UrlNormalizer {

    /**
     * Normalizes the specified URL.
     *
     * @param url The URL to normalize, may be {@code null}.
     * @return The normalized URL or {@code null} if the input was {@code null}.
     */
    String normalize(String url);

# Exceptions - `HTTPException` and `WebSocketException`

These are the exceptions that you can raise to show errors to the client.

When you raise an exception, as would happen with normal Python, the rest of the execution is aborted. This way you can raise these exceptions from anywhere in the code to abort a request and show the error to the client.

You can use:

* `HTTPException`
* `WebSocketException`

# FastAPI in Containers - Docker { #fastapi-in-containers-docker }

When deploying FastAPI applications a common approach is to build a **Linux container image**. It's normally done using <a href="https://www.docker.com/" class="external-link" target="_blank">**Docker**</a>. You can then deploy that container image in one of a few possible ways.

Using Linux containers has several advantages including **security**, **replicability**, **simplicity**, and others.

/// tip

	margin-top: 0;
}

#result .title a:visited {
	color: #014c8c;
}

#result .body {
	display: flex;
	align-items: flex-start;
}

#result .site cite {
	color: #093;
	font-style: normal;
}

#result .more {
	display: none;
}

#result .info {
	font-size: 80%;
}

#result .url-copy {
	color: #007bff;
}

#result .url-copied {
	color: #2c974b;
}

        };
    }

    private static Integer toInteger(final String s) {
        if (StringUtil.isEmpty(s)) {
            return null;
        }
        return Integer.valueOf(DecimalFormatUtil.normalize(s));
    }

    /**
     * Converts to {@literal int}.
     *
     * @param o
     *            The object to convert
     * @return The converted {@literal int}
     */

                bufferIndex += ((AndXServerMessageBlock) this.andx).readAndXWireFormat(buffer, bufferIndex);
            } else {

                /*
                 * Just a plain smb. Read it as normal.
                 */

                buffer[bufferIndex++] = (byte) (this.andx.wordCount & 0xFF);

                if ((this.andx.wordCount != 0) && (this.andx.wordCount > 2)) {

{* ../../docs_src/settings/app02_an_py39/main.py hl[6,12:13] *}

/// tip

We'll discuss the `@lru_cache` in a bit.

For now you can assume `get_settings()` is a normal function.

///

And then we can require it from the *path operation function* as a dependency and use it anywhere we need it.

{* ../../docs_src/settings/app02_an_py39/main.py hl[17,19:21] *}

 *
 * <p>We can't use {@code PartiallyGwtIncompatible} because then the GWT compiler wouldn't recognize
 * it as a {@code GwtIncompatible} annotation. And for {@code Futures.catching}, we need the GWT
 * compiler to autostrip the normal server method in order to expose the special, inherited GWT
 * version.
 */
@GwtCompatible
final class Partially {
  /**
   * The presence of this annotation on an API indicates that the method <i>may</i> be used with the

        }
    }

    private static Double toDouble(final String s) {
        if (StringUtil.isEmpty(s)) {
            return null;
        }
        return Double.valueOf(DecimalFormatUtil.normalize(s));
    }

    /**
     * Converts to {@literal double}.
     *
     * @param o
     *            The object to convert
     * @return The converted {@literal double}
     */