```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

Using `Optional[str]` instead of just `str` will let the editor help you detect errors where you could be assuming that a value is always a `str`, when it could actually be `None` too.

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

     *
     * @param paramMap the data store parameters
     * @param dataMap the document data to store
     * @throws DataStoreException if required fields are missing or other errors occur
     */
    @Override
    public void store(final DataStoreParams paramMap, final Map<String, Object> dataMap) {
        final SystemHelper systemHelper = ComponentUtil.getSystemHelper();

     */
    protected enum Result {
        /** Thumbnail was successfully generated */
        OK,
        /** Thumbnail generation failed due to processing errors */
        FAILED,
        /** Image dimensions do not meet validation requirements */
        INVALID_SIZE,
        /** No valid image data was found in the input */
        NO_IMAGE;
    }

                System.arraycopy(data, offset + 8, addr, 0, 16);
                return InetAddress.getByAddress(addr);
            }
        } catch (Exception e) {
            // Ignore parsing errors
        }
        return null;
    }

    private boolean checkRSSCapability() {
        // Platform-specific RSS detection - simplified implementation
        try {

    }

    /**
     * Creates a synonym item from the provided form data with validation.
     *
     * @param form the create form containing synonym data
     * @param hook the validation error hook for handling errors
     * @return OptionalEntity containing the created synonym item or empty if creation failed
     */
    protected OptionalEntity<SynonymItem> createSynonymItem(final CreateForm form, final VaErrorHook hook) {
        try {

```

Let's say that now the file `main.py` with your **FastAPI** app has some other **path operations**.

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

//// tab | Python 3.10+

```Python
{!> ../../docs_src/app_testing/app_b_an_py310/main.py!}
```

////

//// tab | Python 3.9+

* **Rápido de programar**: Aumenta la velocidad para desarrollar funcionalidades en aproximadamente un 200% a 300%. *
* **Menos bugs**: Reduce en aproximadamente un 40% los errores inducidos por humanos (desarrolladores). *
* **Intuitivo**: Gran soporte para editores. <abbr title="también conocido como autocompletado, IntelliSense">Autocompletado</abbr> en todas partes. Menos tiempo depurando.

  }

  /**
   * We had a bug where we'd perform infinite retries of route that fail with connection shutdown
   * errors. The problem was that the logic that decided whether to reuse a route didn't track
   * certain HTTP/2 errors. https://github.com/square/okhttp/issues/5547
   */
  @ParameterizedTest
  @ArgumentsSource(ProtocolParamProvider::class)

			if sort.SearchStrings(closestCommands, value) < len(closestCommands) {
				continue
			}
			// 2 is arbitrary and represents the max
			// allowed number of typed errors
			if words.DamerauLevenshteinDistance(command, value) < 2 {
				closestCommands = append(closestCommands, value)
			}
		}

		return closestCommands
	}

	// Register all commands.

                } catch (Exception e) {
                    log.debug("Error in async notification monitoring for {}: {}", registrationId, e.getMessage());

                    // Exponential backoff on errors: max 30 seconds, based on consecutive failures
                    try {
                        int failures = Math.min(registration.getHeartbeatFailures(), MAX_FAILURE_LIMIT);