// Verify iterator still works after multiple removes
        assertFalse(emptyIterator.hasNext(), "Iterator should still work after multiple removes");
        assertNull(emptyIterator.next(), "Iterator should still return null after multiple removes");
    }

    @Test
    @DisplayName("EmptyIterator should maintain state after all operations")
    void testStateConsistencyAfterOperations() {

		t.Fatalf("Blog should has three tags after Append")
	}

	if DB.Model(&blog).Association("SharedTags").Count() != 3 {
		t.Fatalf("Blog should has three tags after Append")
	}

	if DB.Model(&blog2).Association("SharedTags").Count() != 3 {
		t.Fatalf("Blog should has three tags after Append")
	}

	var tags []Tag
	DB.Model(&blog).Association("SharedTags").Find(&tags)

    CountingRunnable after = new CountingRunnable();

    future.addListener(before, directExecutor());
    future.setFuture(delegate);
    future.addListener(inBetween, directExecutor());
    delegate.set(1);
    future.addListener(after, directExecutor());

    before.assertRun();
    inBetween.assertRun();
    after.assertRun();
  }

        // Test release (still in use because of initial transport acquire)
        session.release();
        assertTrue(session.isInUse(), "Session should still be in use after one release");

        // Test final release
        session.release();
        assertFalse(session.isInUse(), "Session should not be in use after all releases");

				}
			} else if idx := getRIndex(names, c.after); idx != -1 {
				// if after callback exists but haven't sorted
				// set after callback's before callback to current callback
				after := cs[idx]

				if after.before == "" {
					after.before = c.name
				}

				if err := sortCallback(after); err != nil {
					return err
				}

**FastAPI** provides it as a convenience for you, the developer. But it comes directly from Starlette.

///

### Before and after the `response` { #before-and-after-the-response }

You can add code to be run with the `request`,  before any *path operation* receives it.

And also after the `response` is generated, before returning it.

            task = withLock {
              afterRun(task, delayNanos, true)
              awaitTaskToRun()
            } ?: return
          }
        } catch (thrown: Throwable) {
          // A task failed. Update execution state and re-throw the exception.
          withLock {
            afterRun(task, -1L, false)
          }
          if (thrown is InterruptedException) {

            // The rate limiter should still be functional after concurrent access
            assertTrue(concurrentLimiter.checkAttempt("finaluser", "192.168.3.1"),
                    "Rate limiter should still be functional after concurrent operations");

            // Verify that the rate limiter tracked some activity

        }

        // Call the method under test
        d.readBytesWireFormat(buf, 0);

        // After a full read both flags should be set and hasMore should be false
        assertTrue(d.getParametersDone(), "parametersDone should be true after reading");
        assertTrue(d.getDataDone(), "dataDone should be true after reading");
        assertFalse(d.getHasMore(), "hasMore should be false when both packets are fully read");
    }

The same way, you can define logic (code) that should be executed when the application is **shutting down**. In this case, this code will be executed **once**, **after** having handled possibly **many requests**.

Because this code is executed before the application **starts** taking requests, and right after it **finishes** handling requests, it covers the whole application **lifespan** (the word "lifespan" will be important in a second 😉).