engine = create_engine(sqlite_url, connect_args=connect_args)


def create_db_and_tables():
    SQLModel.metadata.create_all(engine)


def get_session():
    with Session(engine) as session:
        yield session


app = FastAPI()


@app.on_event("startup")
def on_startup():
    create_db_and_tables()


@app.post("/heroes/")

engine = create_engine(sqlite_url, connect_args=connect_args)


def create_db_and_tables():
    SQLModel.metadata.create_all(engine)


def get_session():
    with Session(engine) as session:
        yield session


app = FastAPI()


@app.on_event("startup")
def on_startup():
    create_db_and_tables()


@app.post("/heroes/", response_model=HeroPublic)

          taskRunner: TaskRunner,
          nanos: Long,
        ) {
          taskRunner.assertThreadHoldsLock()
          check(waitingCoordinatorTask == null)
          if (nanos == 0L) return

          // Yield until notified, interrupted, or the duration elapses.
          val waitUntil = nanoTime + nanos
          val self = currentTask
          waitingCoordinatorTask = self
          waitingCoordinatorNotified = false

engine = create_engine(sqlite_url, connect_args=connect_args)


def create_db_and_tables():
    SQLModel.metadata.create_all(engine)


def get_session():
    with Session(engine) as session:
        yield session


SessionDep = Annotated[Session, Depends(get_session)]
app = FastAPI()


@app.on_event("startup")
def on_startup():
    create_db_and_tables()

1. This is the generator function. It's a "generator function" because it contains `yield` statements inside.
2. By using a `with` block, we make sure that the file-like object is closed after the generator function is done. So, after it finishes sending the response.
3. This `yield from` tells the function to iterate over that thing named `file_like`. And then, for each part iterated, yield that part as coming from this generator function (`iterfile`).

```{ .python .annotate hl_lines="2  10-12  14" }
{!../../docs_src/custom_response/tutorial008.py!}
```

1️⃣. 👉 🚂 🔢. ⚫️ "🚂 🔢" ↩️ ⚫️ 🔌 `yield` 📄 🔘.
2️⃣. ⚙️ `with` 🍫, 👥 ⚒ 💭 👈 📁-💖 🎚 📪 ⏮️ 🚂 🔢 🔨. , ⏮️ ⚫️ 🏁 📨 📨.
3️⃣. 👉 `yield from` 💬 🔢 🔁 🤭 👈 👜 🌟 `file_like`. & ⤴️, 🔠 🍕 🔁, 🌾 👈 🍕 👟 ⚪️➡️ 👉 🚂 🔢.

    , ⚫️ 🚂 🔢 👈 📨 "🏭" 👷 🕳 🙆 🔘.

* It can do something to that **response** or run any needed code.
* Then it returns the **response**.

/// note | "Technical Details"

If you have dependencies with `yield`, the exit code will run *after* the middleware.

If there were any background tasks (documented later), they will run *after* all the middleware.

///

## Create a middleware

* ⚫️ 💪 ⤴️ 🕳 👈 **📨** ⚖️ 🏃 🙆 💪 📟.
* ⤴️ ⚫️ 🚶‍♀️ **📨** 🛠️ 🎂 🈸 ( *➡ 🛠️*).
* ⚫️ ⤴️ ✊ **📨** 🏗 🈸 ( *➡ 🛠️*).
* ⚫️ 💪 🕳 👈 **📨** ⚖️ 🏃 🙆 💪 📟.
* ⤴️ ⚫️ 📨 **📨**.

/// note | "📡 ℹ"

🚥 👆 ✔️ 🔗 ⏮️ `yield`, 🚪 📟 🔜 🏃 *⏮️* 🛠️.

🚥 📤 🙆 🖥 📋 (📄 ⏪), 👫 🔜 🏃 *⏮️* 🌐 🛠️.

///

## ✍ 🛠️

✍ 🛠️ 👆 ⚙️ 👨‍🎨 `@app.middleware("http")` 🔛 🔝 🔢.

🛠️ 🔢 📨:

*  `request`.

 * accounts. SIDs are commonly represented using a textual format such as
 * <tt>S-1-5-21-1496946806-2192648263-3843101252-1029</tt> but they may
 * also be resolved to yield the name of the associated Windows account
 * such as <tt>Administrators</tt> or <tt>MYDOM\alice</tt>.
 * <p>
 * Consider the following output of <tt>examples/SidLookup.java</tt>:
 * 
 * <pre>

                        "timed out waiting for other threads to block"
                            + " synchronizing on supplier"));
                break;
              }
              Thread.yield();
            }
            count.getAndIncrement();
            return Boolean.TRUE;
          }
        };

    final Supplier<Boolean> memoizedSupplier = memoizer.apply(supplier);