Como ejemplo, tomemos esta función:

{* ../../docs_src/python_types/tutorial009c_py39.py hl[1,4] *}

El parámetro `name` está definido como `Optional[str]`, pero **no es opcional**, no puedes llamar a la función sin el parámetro:

```Python
say_hi()  # ¡Oh, no, esto lanza un error! 😱
```

///

Aquí definimos la configuración `env_file` dentro de tu clase Pydantic `Settings`, y establecemos el valor en el nombre del archivo con el archivo dotenv que queremos usar.

          // getDeclaredField to throw a NoSuchFieldException when the field is definitely there.
          // For these users fallback to a suboptimal implementation, based on synchronized. This
          // will be a definite performance hit to those users.
          thrownAtomicReferenceFieldUpdaterFailure = atomicReferenceFieldUpdaterFailure;
          helper = new SynchronizedHelper();
        }
      }
    } else {
      /*

          // getDeclaredField to throw a NoSuchFieldException when the field is definitely there.
          // For these users fallback to a suboptimal implementation, based on synchronized. This
          // will be a definite performance hit to those users.
          thrownAtomicReferenceFieldUpdaterFailure = atomicReferenceFieldUpdaterFailure;
          helper = new SynchronizedHelper();
        }
      }
    }

If you check the previous app, in the UI you can see that, up to now, it lets the client decide the `id` of the `Hero` to create. 😱

We shouldn't let that happen, they could overwrite an `id` we already have assigned in the DB. Deciding the `id` should be done by the **backend** or the **database**, **not by the client**.

Additionally, we create a `secret_name` for the hero, but so far, we are returning it everywhere, that's not very **secret**... 😅

Quando você quiser chamar uma função `async def`, você tem que "esperar" ela. Então, isso não funcionará:

```Python
# Isso não irá funcionar, porquê get_burgers foi definido com: async def
burgers = get_burgers(2)
```

---

Então, se você está usando uma biblioteca que diz que você pode chamá-la com `await`, você precisa criar as *funções de operação de rota* com `async def`, como em:

1) If the text surrounded by the abbr element is an abbreviation (the text may be surrounded by further HTML or Markdown markup or quotes, for example «<code>text</code>» or «`text`» or «"text"», ignore that further markup when deciding if the text is an abbreviation), and if the description (the text inside the title attribute) contains the full phrase for this abbreviation, then append a dash («–») to the full phrase, followed by the translation of the full phrase.

        if (existing != null) {
          return existing;
        }
      }
      drainQueue();
      return created;
    }

    // N.B. Draining the queue is only necessary to ensure that we don't accumulate empty references
    // in the array. We could skip this if we decide we don't care about holding on to Reference
    // objects indefinitely.

            }
        }

        @Override
        public void close() {
            this.executor.close();
        }

        /**
         * Processes a single build step, deciding whether to schedule it for execution or skip it.
         *
         * @param step The build step to process
         */
        private void processStep(BuildStep step) {

{* ../../docs_src/response_model/tutorial006_py310.py hl[29,35] *}

## Resumen { #recap }

Usa el parámetro `response_model` del *decorador de path operation* para definir modelos de response y especialmente para asegurarte de que los datos privados sean filtrados.