app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):

      // When a listener is first added, we run a task that will wait for the delegate to finish,
      // and when it is done will run the listeners.
      if (hasListeners.compareAndSet(false, true)) {
        if (delegate.isDone()) {
          // If the delegate is already done, run the execution list immediately on the current
          // thread.
          executionList.execute();
          return;
        }

          <version>4.0.0+</version>
          <required>false</required>
          <description>Default dependency information for projects that inherit from this one. The
            dependencies in this section are not immediately resolved. Instead, when a POM derived
            from this one declares a dependency described by a matching groupId and artifactId, the

`Optional[Something]` é na verdade um atalho para `Union[Something, None]`, eles são equivalentes.

Isso também significa que no Python 3.10, você pode utilizar `Something | None`:

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

    immutable = immutable,
    headerValue = headerValue,
  )
}

/**
 * Returns the next index in this at or after [startIndex] that is a character from
 * [characters]. Returns the input length if none of the requested characters can be found.
 */
private fun String.indexOfElement(
  characters: String,
  startIndex: Int = 0,
): Int {
  for (i in startIndex until length) {
    if (this[i] in characters) {

      taskRunner = taskRunner,
      maxIdleConnections = maxIdleConnections,
      keepAliveDuration = 100L,
      timeUnit = TimeUnit.NANOSECONDS,
      connectionListener = ConnectionListener.NONE,
      exchangeFinderFactory = { pool, address, user ->
        FastFallbackExchangeFinder(
          routePlanner ?: RealRoutePlanner(
            taskRunner = taskRunner,
            connectionPool = pool,

    route: Route?,
    response: Response,
  ): Request?

  companion object {
    /** An authenticator that knows no credentials and makes no attempt to authenticate. */
    @JvmField
    val NONE: Authenticator = AuthenticatorNone()

    private class AuthenticatorNone : Authenticator {
      override fun authenticate(
        route: Route?,
        response: Response,
      ): Request? = null
    }

	r := rand.New(rand.NewSource(time.Now().UnixNano()))

	retryCtx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()

	for {
		select {
		case <-retryCtx.Done():
			// Caller context canceled or we timedout,
			// return false anyways for both situations.
			return false
		default:
			if lm.lock(id, source, isWriteLock) {
				return true
			}

	lkTimer := time.NewTimer(lockMaintenanceInterval)
	// Stop the timer upon returning.
	defer lkTimer.Stop()

	for {
		// Verifies every minute for locks held more than 2 minutes.
		select {
		case <-ctx.Done():
			return
		case <-lkTimer.C:
			globalLockServer.expireOldLocks(lockValidityDuration)

			// Reset the timer for next cycle.
			lkTimer.Reset(lockMaintenanceInterval)
		}
	}

    "bar": {"id": "bar", "title": "Bar", "description": "The bartenders"},
}

app = FastAPI()


class Item(BaseModel):
    id: str
    title: str
    description: Union[str, None] = None


@app.get("/items/{item_id}", response_model=Item)
async def read_main(item_id: str, x_token: str = Header()):
    if x_token != fake_secret_token: