* }</pre>
 *
 * <h3>Comparison to alternatives</h3>
 *
 * <p><b>Note:</b> In some cases the differences explained below can be subtle. When it's unclear
 * which approach to use, <b>don't worry</b> too much about it; just pick something that seems
 * reasonable and it will be fine.
 *
 * <ul>
 *   <li>If checking whether the <i>caller</i> has violated your method or constructor's contract

  private static final class LegacyAsyncDispatcher extends Dispatcher {

    // This dispatcher matches the original dispatch behavior of AsyncEventBus.
    //
    // We can't really make any guarantees about the overall dispatch order for this dispatcher in
    // a multithreaded environment for a couple of reasons:
    //
    // 1. Subscribers to events posted on different threads can be interleaved with each other

Use the `tags` parameter with your *path operations* (and `APIRouter`s) to assign them to different tags:

```Python hl_lines="21  26"
{!../../docs_src/metadata/tutorial004.py!}
```

/// info

Read more about tags in [Path Operation Configuration](path-operation-configuration.md#tags){.internal-link target=_blank}.

///

### Check the docs

Now, if you check the docs, they will show all the additional metadata:

/// info

You can read more about the Starlette `lifespan` handlers in <a href="https://www.starlette.io/lifespan/" class="external-link" target="_blank">Starlette's  Lifespan' docs</a>.

● Config ... ✔ 
● Drive ... ✔ 
● Net ... ✔ 
*********************************************************************************
                                   WARNING!!
     ** THIS FILE MAY CONTAIN SENSITIVE INFORMATION ABOUT YOUR ENVIRONMENT ** 
     ** PLEASE INSPECT CONTENTS BEFORE SHARING IT ON ANY PUBLIC FORUM **
*********************************************************************************

	errUnexpectedInvalidNode  = errors.New("Unexpected node value")
	errInvalidKeypath         = errors.New("A provided keypath is invalid")
)

// qProp contains analysis info about an SQL term.
type qProp struct {
	isAggregation, isRowFunc bool

	err error
}

// `combine` combines a pair of `qProp`s, so that errors are
// propagated correctly, and checks that an aggregation is not being

      // timed out. e.g. if we weren't event able to grab the lock within the timeout we would never
      // even check the guard. I don't think we care too much about this use case but it could lead
      // to a confusing error message.
      throw new TimeoutException("Timed out waiting for " + this + " to reach the RUNNING state.");
    }
  }

  @Override

 * }</pre>
 *
 * <h3>Comparison to alternatives</h3>
 *
 * <p><b>Note:</b> In some cases the differences explained below can be subtle. When it's unclear
 * which approach to use, <b>don't worry</b> too much about it; just pick something that seems
 * reasonable and it will be fine.
 *
 * <ul>
 *   <li>If checking whether the <i>caller</i> has violated your method or constructor's contract

Violations of the Code of Conduct can occur in any setting, even those unrelated to the project. We will only consider complaints about conduct that has occurred within one year of the report.


## Enforcement

////

//// tab | Python 3.8+

```Python hl_lines="30-35"
{!> ../../docs_src/body_updates/tutorial001.py!}
```

////

`PUT` is used to receive data that should replace the existing data.

### Warning about replacing

That means that if you want to update the item `bar` using `PUT` with a body containing:

```Python
{
    "name": "Barz",
    "price": 3,
    "description": None,
}
```