Например, у вас есть файл `main.py`:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

Второй аргумент <a href=«https://docs.python.org/3.8/library/os.html#os.getenv» class=«external-link» target=«_blank»>`os.getenv()`</a> - это возвращаемое по умолчанию значение.

    You can also use it yourself, for example to convert objects before saving them
    in a database that supports only JSON.

    Read more about it in the
    [FastAPI docs for JSON Compatible Encoder](https://fastapi.tiangolo.com/tutorial/encoder/).
    """
    custom_encoder = custom_encoder or {}
    if custom_encoder:
        if type(obj) in custom_encoder:

		if pubkey == nil {
			return nil, fmt.Errorf("No public key found for kid %s", kid)
		}
		return pubkey, nil
	}

	pCfg, ok := r.arnProviderCfgsMap[arn]
	if !ok {
		return fmt.Errorf("Role %s does not exist", arn)
	}

	mclaims := jwtgo.MapClaims(claims)
	jwtToken, err := jp.ParseWithClaims(token, &mclaims, keyFuncCallback)
	if err != nil {
		// Re-populate the public key in-case the JWKS

	}

	if typeAvailable != "none" {
		expectedType := "hash"
		if r.Format == event.AccessFormat {
			expectedType = "list"
		}

		if typeAvailable != expectedType {
			return fmt.Errorf("expected type %v does not match with available type %v", expectedType, typeAvailable)
		}
	}

	return nil
}

// RedisTarget - Redis target.
type RedisTarget struct {
	initOnce once.Init

	id         event.TargetID

	}
	if err = e.encoder().Encode(encoded); err != nil {
		return nil, err
	}
	return encoded, nil
}

// DecodeDataBlocks decodes the given erasure-coded data.
// It only decodes the data blocks but does not verify them.
// It returns an error if the decoding failed.
func (e *Erasure) DecodeDataBlocks(data [][]byte) error {
	isZero := 0
	for _, b := range data {
		if len(b) == 0 {
			isZero++
			break
		}
	}

                logger.debug("Failed to validate a file.", e);
            }
        }
        return false;
    }

    /**
     * Generates SitemapSet instance.
     *
     * This method does not close the input stream.
     *
     * @param in Input stream for a sitemap
     * @return a sitemap set
     */
    public SitemapSet parse(final InputStream in) {
        return parse(in, true);
    }

in a declaration, but it does not introduce a binding and thus is not declared.
In the package block, the identifier <code>init</code> may only be used for
<a href="#Package_initialization"><code>init</code> function</a> declarations,
and like the blank identifier it does not introduce a new binding.
</p>

<pre class="ebnf">

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

然后打开位于 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a> 的文档。

你将看到使用了正确路径（和前缀）和正确标签的自动化 API 文档，包括了来自所有子模块的路径：

<img src="https://fastapi.tiangolo.com/img/tutorial/bigger-applications/image01.png">

## 多次使用不同的 `prefix` 包含同一个路由器

        * Uma chave `schema`, que contém como valor o JSON Schema do modelo, sendo este o local correto.
            * O **FastAPI** adiciona aqui a referência dos esquemas JSON globais que estão localizados em outro lugar, ao invés de incluí-lo diretamente. Deste modo, outras aplicações e clientes podem utilizar estes esquemas JSON diretamente, fornecer melhores ferramentas de geração de código, etc.

  public void forTree_acceptsDirectedGraph() throws Exception {
    MutableGraph<String> graph = GraphBuilder.directed().build();
    graph.putEdge("a", "b");

    Traverser.forTree(graph); // Does not throw
  }

  @Test
  public void forTree_withUndirectedGraph_throws() throws Exception {
    MutableGraph<String> graph = GraphBuilder.undirected().build();
    graph.putEdge("a", "b");