t.Fatalf("bytepool size invalid: got %v want %v", len(bp.c), size)
	}

	// lets drain the buf channel first before we validate invalid buffers.
	for range size {
		bp.Get() // discard
	}

	// Try putting some invalid buffers into pool
	bp.Put(make([]byte, bp.w, bp.wcap-1)) // wrong capacity is rejected (less)
	bp.Put(make([]byte, bp.w, bp.wcap+1)) // wrong capacity is rejected (more)

## 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 }

    "JDK_HOME",
    "JRE_HOME",
    "CommonProgramFiles",
    "CommonProgramFiles(x86)",
    "CommonProgramW6432",
    "ProgramData",
    "ProgramFiles",
    "ProgramFiles(x86)",
    // Simply putting PATH there isn't enough. Windows has case-insensitive env vars but something else fails if the Path variable is published as PATH for test tasks.
    OperatingSystem.current().pathVar,
    "PATHEXT",

    // If we successfully add the computed element, we're done.
    val newTags = tags.plus(type, computed)
    if (compareAndSet(tags, newTags)) return computed

    // We lost the race. Possibly to other code that was putting a *different* key. Try again!
  }

### `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
```

    /**
     * Default mode for combining children DOMs during merge.
     * When element names match, the process will try to merge the element data,
     * rather than putting the dominant and recessive elements as siblings.
     */
    public static final String DEFAULT_CHILDREN_COMBINATION_MODE = CHILDREN_COMBINATION_MERGE;

    /** Attribute name controlling how the element itself is combined */

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

{* ../../docs_src/events/tutorial003_py39.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*.

  for (i in 0 until length) {
    val c = this[i]
    if (c <= '\u001f' || c >= '\u007f') {
      return i
    }
  }
  return -1
}

/** Returns true if we should void putting this this header in an exception or toString(). */
internal fun isSensitiveHeader(name: String): Boolean =
  name.equals("Authorization", ignoreCase = true) ||
    name.equals("Cookie", ignoreCase = true) ||

    @SuppressWarnings("SynchronizeOnNonFinalField")
    public T get() {
      // Another variant of Double Checked Locking.
      //
      // We use two volatile reads. We could reduce this to one by
      // putting our fields into a holder class, but (at least on x86)
      // the extra memory consumption and indirection are more
      // expensive than the extra volatile reads.
      long nanos = expirationNanos;