{* ../../docs_src/openapi_callbacks/tutorial001_py310.py hl[14:16,19:20,26:30] *}

There are 2 main differences from a normal *path operation*:

* It doesn't need to have any actual code, because your app will never call this code. It's only used to document the *external API*. So, the function could just have `pass`.

	// This wrapper uses complicated machinery to run iOS binaries. It
	// works, but only when running one binary at a time.
	// Use a file lock to make sure only one wrapper is running at a time.
	//
	// The lock file is never deleted, to avoid concurrent locks on distinct
	// files with the same path.
	lockName := filepath.Join(os.TempDir(), "go_ios_exec-"+deviceID+".lock")
	lock, err = os.OpenFile(lockName, os.O_CREATE|os.O_RDONLY, 0666)

            DfsReferralResponseBuffer buffer2 = response.getDfsResponse();

            assertSame(buffer1, buffer2);
        }

        @Test
        @DisplayName("Should never return null DfsResponse")
        void testGetDfsResponseNeverNull() {
            assertNotNull(response.getDfsResponse());
        }

        @Test

		}
	}
	return false
}

// enforceRetentionBypassForDelete enforces whether an existing object under governance can be deleted
// with governance bypass headers set in the request.
// Objects under site wide WORM can never be overwritten.
// For objects in "Governance" mode, overwrite is allowed if a) object retention date is past OR
// governance bypass headers are set and user has governance bypass permissions.

			if p != j {
				t.Errorf("IndexByte(%q, %d) = %d", b[i:i+15], 100+j, p)
			}
		}
		for j := 0; j < 15; j++ {
			b[i+j] = 0
		}
	}
	// Make sure matches outside the slice never trigger.
	for i := 0; i <= len(b)-15; i++ {
		for j := 0; j < 15; j++ {
			b[i+j] = 1
		}
		for j := 0; j < 15; j++ {
			p := IndexByte(b[i:i+15], byte(0))
			if p != -1 {

Actually, all (or most) of the web frameworks work in this same way.

You never call those functions directly. They are called by your framework (in this case, **FastAPI**).

    future1.set(1L);
    future1 = null;
    future2.set(2L);
    future2 = null;

    /*
     * Futures should be collected even if combiner never runs. This is kind of a silly test, since
     * the combiner is almost certain to hold its own reference to the futures, and a real app would

    future1.set(1L);
    future1 = null;
    future2.set(2L);
    future2 = null;

    /*
     * Futures should be collected even if combiner never runs. This is kind of a silly test, since
     * the combiner is almost certain to hold its own reference to the futures, and a real app would

   * Future}.
   *
   * <p>Note that, even if the supplied future is cancelled and it causes this future to complete,
   * it will never trigger interruption behavior. In particular, it will not cause this future to
   * invoke the {@link #interruptTask} method, and the {@link #wasInterrupted} method will not
   * return {@code true}.
   *

      hashTableKToV[keyBucket] = dest;
    } else {
      int prevInBucket = hashTableKToV[keyBucket];
      for (int entryInBucket = nextInBucketKToV[prevInBucket];
          /* should never reach end */ ;
          entryInBucket = nextInBucketKToV[entryInBucket]) {
        if (entryInBucket == src) {
          nextInBucketKToV[prevInBucket] = dest;
          break;
        }