## Reduce duplication

Reducing code duplication is one of the core ideas in **FastAPI**.

As code duplication increments the chances of bugs, security issues, code desynchronization issues (when you update in one place but not in the others), etc.

And these models are all sharing a lot of the data and duplicating attribute names and types.

We could do better.

Para retornar ao cliente *responses* HTTP com erros, use o `HTTPException`.

### Import `HTTPException`

```Python hl_lines="1"
{!../../../docs_src/handling_errors/tutorial001.py!}
```

### Lance o `HTTPException` no seu código.

`HTTPException`, ao fundo, nada mais é do que a conjunção entre uma exceção comum do Python e informações adicionais relevantes para APIs.

// ExtraValue masks the value so protobuf can generate
// +protobuf.nullable=true
// +protobuf.options.(gogoproto.goproto_stringer)=false
message ExtraValue {
  // items, if empty, will result in an empty slice

  repeated string items = 1;
}

// LocalSubjectAccessReview checks whether or not a user or group can perform an action in a given namespace.

- sends UDS events to ztunnel via a socket whenever a pod is enabled for ambient mesh (whether from CNI plugin or node watcher), instructing ztunnel to create the "tube" socket.

The ambient CNI agent is the only place where ambient network config and pod redirection machinery happens.

## What is "Form Data"

The way HTML forms (`<form></form>`) sends the data to the server normally uses a "special" encoding for that data, it's different from JSON.

**FastAPI** will make sure to read that data from the right place instead of JSON.

!!! note "Technical Details"
    Data from forms is normally encoded using the "media type" `application/x-www-form-urlencoded` when it doesn't include files.

      val urlHost = url.host
      if (domain == null) {
        domain = urlHost
      } else if (!domainMatch(urlHost, domain)) {
        return null // No domain match? This is either incompetence or malice!
      }

      // If the domain is a suffix of the url host, it must not be a public suffix.
      if (urlHost.length != domain.length &&
        PublicSuffixDatabase.get().getEffectiveTldPlusOne(domain) == null

    val editor = cache.edit("k1")!!
    editor.setString(0, "a")
    editor.setString(1, "a")
    cache.evictAll()

    // Create a new value in its place.
    set("k1", "bb", "bb")
    assertThat(cache.size()).isEqualTo(4)

    // Committing the detached editor should not change the cache's size.
    editor.commit()
    assertThat(cache.size()).isEqualTo(4)

know with an error, **Python** will also complain if you run it without passing the required parameter.

When you don't use `Annotated` and instead use the **(old) default value style**, if you call that function without FastAPI in **other place**, you have to **remember** to pass the arguments to the function for it to work correctly, otherwise the values will be different from what you expect (e.g. `QueryInfo` or something similar instead of `str`). And your editor won't complain, and Python...

  // can have their pods stopped for an update at any given time. The update
  // starts by stopping at most 30% of those DaemonSet pods and then brings
  // up new DaemonSet pods in their place. Once the new pods are available,
  // it then proceeds onto other DaemonSet pods, thus ensuring that at least
  // 70% of original number of DaemonSet pods are available at all times during
  // the update.
  // +optional

# shared object directly.
#
# For example, from Python tf.load_op_library loads a custom op library (via
# dlopen() on Linux), the library finds libtensorflow_framework.so (no
# filesystem search takes place, since libtensorflow_framework.so has already
# been loaded by pywrap_tensorflow) and registers its ops and kernels via
# REGISTER_OP and REGISTER_KERNEL_BUILDER (which use symbols from