// Capability (4 bytes)
        bb.putInt(capability);

        // Reserved (4 bytes) - must be 0
        bb.putInt(0);

        // LinkSpeed (8 bytes) - in bits per second
        bb.putLong((long) linkSpeed * 1000000L);

        // SockAddr_Storage (128 bytes)
        encodeSockaddr(buffer, 24);

        return buffer;
    }

    /**
     * Parse network interface info from encoded bytes

            }
            baos.write(channel.getLocalInterface().getAddress().getAddress());
            baos.write(channel.getRemoteInterface().getAddress().getAddress());
            baos.write(ByteBuffer.allocate(8).putLong(System.currentTimeMillis()).array());
        } catch (IOException e) {
            // Should not happen with ByteArrayOutputStream
            log.error("Error creating binding info", e);
        }

            final long counter = this.nonceCounter.incrementAndGet();
            final ByteBuffer buffer = ByteBuffer.wrap(nonce);
            buffer.order(java.nio.ByteOrder.LITTLE_ENDIAN);
            buffer.putLong(counter);
            // Remaining bytes (if any) stay zero-padded
        }

        return nonce;
    }

    /**
     * Generate a secure random nonce for initial session setup.

## What Does Deployment Mean { #what-does-deployment-mean }

To **deploy** an application means to perform the necessary steps to make it **available to the users**.

For a **web API**, it normally involves putting it in a **remote machine**, with a **server program** that provides good performance, stability, etc, so that your **users** can **access** the application efficiently and without interruptions or problems.

# Additional Status Codes { #additional-status-codes }

By default, **FastAPI** will return the responses using a `JSONResponse`, putting the content you return from your *path operation* inside of that `JSONResponse`.

It will use the default status code or the one you set in your *path operation*.

## Additional status codes { #additional-status-codes_1 }

We create an async function `lifespan()` with `yield` like this:

{* ../../docs_src/events/tutorial003.py hl[16,19] *}

Here we are simulating the expensive *startup* operation of loading the model by putting the (fake) model function in the dictionary with machine learning models before the `yield`. This code will be executed **before** the application **starts taking requests**, during the *startup*.

### `Union` in Python 3.10 { #union-in-python-3-10 }

In this example we pass `Union[PlaneItem, CarItem]` as the value of the argument `response_model`.

Because we are passing it as a **value to an argument** instead of putting it in a **type annotation**, we have to use `Union` even in Python 3.10.

If it was in a type annotation we could have used the vertical bar, as:

```Python
some_variable: PlaneItem | CarItem
```

Previous versions of FastAPI (before <abbr title="before 2023-03">0.95.0</abbr>) required you to use `Query` as the default value of your parameter, instead of putting it in `Annotated`, there's a high chance that you will see code using it around, so I'll explain it to you.

/// tip

Then the cashier 💁 says "I'm finished with doing the burgers" by putting your number on the counter's display, but you don't jump like crazy immediately when the displayed number changes to your turn number. You know no one will steal your burgers because you have the number of your turn, and they have theirs.

///

## Type Hints with Metadata Annotations { #type-hints-with-metadata-annotations }

Python also has a feature that allows putting **additional <abbr title="Data about the data, in this case, information about the type, e.g. a description.">metadata</abbr>** in these type hints using `Annotated`.

//// tab | Python 3.9+