<div class="termy">

```console
$ cd ~/code/prisoner-of-azkaban

$ python main.py

// Error importing sirius, it's not installed 😱
Traceback (most recent call last):
    File "main.py", line 1, in <module>
        import sirius
```

</div>

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009c.py!}
```

🔢 `name` 🔬 `Optional[str]`, ✋️ ⚫️ **🚫 📦**, 👆 🚫🔜 🤙 🔢 🍵 🔢:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

`name` 🔢 **✔** (🚫 *📦*) ↩️ ⚫️ 🚫 ✔️ 🔢 💲. , `name` 🚫 `None` 💲:

```Python
say_hi(name=None)  # This works, None is valid 🎉
```

                            } else if (logger.isWarnEnabled()) {
                                logger.warn(msg);
                            } else if (logger.isErrorEnabled()) {
                                logger.error(msg);
                            }
                        }
                    } catch (final Exception e) {
                        logger.warn(e.getLocalizedMessage());
                    }

  // 'test' to demonstrate some potentially ambiguous overloads.  This 'test' is kind of strange,
  // but essentially each line will be a call to a Preconditions method that, but for a documented
  // change would be a compiler error.
  // See http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12.2 for the spec on
  // how javac selects overloads
  @SuppressWarnings("null")
  public void overloadSelection() {

  // 'test' to demonstrate some potentially ambiguous overloads.  This 'test' is kind of strange,
  // but essentially each line will be a call to a Preconditions method that, but for a documented
  // change would be a compiler error.
  // See http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12.2 for the spec on
  // how javac selects overloads
  @SuppressWarnings("null")
  public void overloadSelection() {

            // When & Then
            assertThrows(CIFSException.class, () -> transportPool.getChallenge(context, address));
        }
    }

    @Nested
    @DisplayName("Edge Cases and Error Handling")
    class EdgeCasesTests {

        @Test
        @DisplayName("Should handle null context")
        void testNullContext() {
            // Given

     * the configuration type and delegates to the appropriate service.
     *
     * @param configId the configuration ID to retrieve
     * @return the CrawlingConfig object or null if not found or on error
     */
    public CrawlingConfig getCrawlingConfig(final String configId) {
        try {
            return crawlingConfigCache.get(configId, () -> {

    //                                                                        ============
    /**
     * Verifies that the provided CRUD mode matches the expected mode.
     * Throws a validation error if the modes do not match.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     */
    protected void verifyCrudMode(final int crudMode, final int expectedMode) {

 * <p>Event subscriber methods must accept only one argument: the event.
 *
 * <p>Subscribers should not, in general, throw. If they do, the EventBus will catch and log the
 * exception. This is rarely the right solution for error handling and should not be relied upon; it
 * is intended solely to help find problems during development.
 *
 * <p>The EventBus guarantees that it will not call a subscriber method from multiple threads

                HttpSession session = req.getSession(false);
                if (session != null && session.getAttribute("npa-workgroup") != null) {
                    throw new IOException("Test error");
                } else {
                    resp.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
                    resp.setHeader("WWW-Authenticate", "NTLM");
                    resp.flushBuffer();