////

//// tab | non-Annotated

```Python
q: Union[str, None] = Query(default=None, min_length=3)
```

////

So, when you need to declare a value as required while using `Query`, you can simply not declare a default value:

//// tab | Python 3.9+

```Python hl_lines="9"
{!> ../../docs_src/query_params_str_validations/tutorial006_an_py39.py!}
```

////

//// tab | Python 3.8+

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-01-swagger-ui-simple.png)

### Tài liệu API thay thế

Và bây giờ, hãy truy cập tới <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>.

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-01-swagger-ui-simple.png)

### 可选的 API 文档

访问 <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>。

你会看到另一个自动生成的文档（由 <a href="https://github.com/Rebilly/ReDoc" class="external-link" target="_blank">ReDoc</a> 生成）：

![ReDoc](https://fastapi.tiangolo.com/img/index/index-02-redoc-simple.png)

## 示例升级

     * (if applicable). This process will essentially remove duplicate repositories by merging them into one equivalent
     * repository. It is worth to point out that merging does not simply choose one of the input repositories and
     * discards the others but actually combines their possibly different policies.
     *
     * @param repositories The original repositories, may be {@code null}.

   * elements left in the iteration.
   *
   * @return {@code null}; a convenience so your {@code computeNext} implementation can use the
   *     simple statement {@code return endOfData();}
   */
  @CanIgnoreReturnValue
  @CheckForNull
  protected final T endOfData() {
    state = State.DONE;
    return null;
  }

  @Override

### Autres formes de code asynchrone

L'utilisation d'`async` et `await` est relativement nouvelle dans ce langage.

Mais cela rend la programmation asynchrone bien plus simple.

Cette même syntaxe (ou presque) était aussi incluse dans les versions modernes de Javascript (dans les versions navigateur et NodeJS).

Mais avant ça, gérer du code asynchrone était bien plus complexe et difficile.

           Shell2Junit License Information

Feb, 2010

shell2junit library and sample code is licensed under Apache License, v.2.0.

(c) 2009 Manolo Carrasco (Manuel Carrasco Moñino)

=====

Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/ 

1. Definitions.

"License" shall mean the terms and conditions for use, reproduction, and 
distribution as defined by Sections 1 through 9 of this document. 

    while (n > 0) {
      long amt = reader.skip(n);
      if (amt == 0) {
        throw new EOFException();
      }
      n -= amt;
    }
  }

  /**
   * Returns a {@link Writer} that simply discards written chars.
   *
   * @since 15.0
   */
  public static Writer nullWriter() {
    return NullWriter.INSTANCE;
  }

  private static final class NullWriter extends Writer {

then
    die "xargs is not available"
fi

# Use "xargs" to parse quoted args.
#
# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
#
# In Bash we could simply go:
#
#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
#   set -- "${ARGS[@]}" "$@"
#
# but POSIX shell has neither arrays nor command substitution, so instead we

         * the 'received' member of the response object will not
         * be set to true indicating the send and sendTransaction
         * methods that the next part should be sent. This is a
         * very indirect and simple batching control mechanism.
         */

        if( andx == null || USE_BATCHING == false ||
                                batchLevel >= getBatchLimit( andx.command )) {
            andxCommand = (byte)0xFF;