注意預設值仍然是 `None`，所以這個參數仍是可選。

不過，現在在 `Annotated` 裡有 `Query(max_length=50)`，我們就告訴 FastAPI 要對這個值做「額外驗證」，最多 50 個字元即可。😎

/// tip | 提示

這裡用的是 `Query()`，因為這是「查詢參數」。稍後你會看到 `Path()`、`Body()`、`Header()`、`Cookie()` 等，它們也接受與 `Query()` 相同的參數。

///

FastAPI 現在會：

- 驗證資料，確保長度最多 50 個字元
- 當資料不合法時，回給用戶端清楚的錯誤
- 在 OpenAPI 的路徑操作中文件化該參數（因此會出現在自動文件 UI）

  ): List<Header> {
    continuation.left = length
    continuation.padding = padding
    continuation.flags = flags
    continuation.streamId = streamId

    // TODO: Concat multi-value headers with 0x0, except COOKIE, which uses 0x3B, 0x20.
    // http://tools.ietf.org/html/draft-ietf-httpbis-http2-17#section-8.1.2.5
    hpackReader.readHeaders()
    return hpackReader.getAndResetHeaderList()
  }

  @Throws(IOException::class)

          continue outer;
        }

        if (atomic.compareAndSet(oldValue, newValue)) {
          return oldValue;
        }
        // value changed
      }
    }
  }

  /**
   * Copies all of the mappings from the specified map to this map. The effect of this call is
   * equivalent to that of calling {@code put(k, v)} on this map once for each mapping from key

   * is unnecessary; for example, {@code copyOf(copyOf(anArrayList))} will copy the data only once.
   * This reduces the expense of habitually making defensive copies at API boundaries. However, the
   * precise conditions for skipping the copy operation are undefined.
   *
   * @throws NullPointerException if any of {@code elements} is null
   * @since 7.0 (source-compatible since 2.0)

      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

}

// DirectioAlignSize - DirectIO alignment needs to be 4K. Defined here as
// directio.AlignSize is defined as 0 in MacOS causing divide by 0 error.
const DirectioAlignSize = 4096

// CopyAligned - copies from reader to writer using the aligned input
// buffer, it is expected that input buffer is page aligned to
// 4K page boundaries. Without passing aligned buffer may cause
// this function to return error.
//

// in tests only.)
TF_CAPI_EXPORT int TF_PickUnusedPortOrDie(void);

// Fast path method that makes constructing a single scalar tensor require less
// overhead and copies.
TF_CAPI_EXPORT extern TFE_TensorHandle* TFE_NewTensorHandleFromScalar(
    TF_DataType data_type, void* data, size_t len, TF_Status* status);

// Specify the server_def that enables collective ops.

* 경로 처리 데코레이터
* 경로 처리 함수

* body
* 요청 body
* 응답 body
* JSON body
* form body
* file body
* 함수 body

* parameter
* body parameter
* path parameter
* query parameter
* cookie parameter
* header parameter
* form parameter
* function parameter

* event
* startup event
* 서버 startup
* shutdown event
* lifespan event

* handler
* event handler

patent infringement, then any patent licenses granted to You under this 
License for that Work shall terminate as of the date such litigation is 
filed. 

4. Redistribution. You may reproduce and distribute copies of the Work or 
Derivative Works thereof in any medium, with or without modifications, and 
in Source or Object form, provided that You meet the following conditions: