## レスポンスモデルのエンコーディングパラメータ

レスポンスモデルにはデフォルト値を設定することができます:

```Python hl_lines="11 13 14"
{!../../docs_src/response_model/tutorial004.py!}
```

* `description: str = None`は`None`がデフォルト値です。
* `tax: float = 10.5`は`10.5`がデフォルト値です。
* `tags: List[str] = []` は空のリスト（`[]`）がデフォルト値です。

しかし、実際に保存されていない場合には結果からそれらを省略した方が良いかもしれません。

  private double sumOfProductsOfDeltas = 0.0;

  /** Adds the given pair of values to the dataset. */
  public void add(double x, double y) {
    // We extend the recursive expression for the one-variable case at Art of Computer Programming
    // vol. 2, Knuth, 4.2.2, (16) to the two-variable case. We have two value series x_i and y_i.

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

	}

	if err = checkPathLength(dirPath); err != nil {
		return err
	}

	if err = reliableRemoveAll(dirPath); err != nil {
		switch {
		case isSysErrNotDir(err):
			// File path cannot be verified since one of
			// the parents is a file.
			return errFileAccessDenied
		case isSysErrPathNotFound(err):
			// This is a special case should be handled only for
			// windows, because windows API does not return "not a

    # - - - - - - - - - -/

    # /- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    # o objectTypeTargetList: (NotRequired - Default databaseInfoMap's)
    #  This property overrides databaseInfoMap's one for ReplaceSchema.
    #    e.g. Synonym of Oracle --> list:{TABLE ; VIEW ; SYNONYM}
    #
    #; objectTypeTargetList = list:{TABLE ; VIEW}
    # - - - - - - - - - -/

/**
 * Models the contents of a `Sec-WebSocket-Extensions` response header. OkHttp honors one extension
 * `permessage-deflate` and four parameters, `client_max_window_bits`, `client_no_context_takeover`,
 * `server_max_window_bits`, and `server_no_context_takeover`.
 *
 * Typically this will look like one of the following:
 *
 * ```
 * Sec-WebSocket-Extensions: permessage-deflate

This tutorial shows you how to use **FastAPI** with most of its features, step by step.

Each section gradually builds on the previous ones, but it's structured to separate topics, so that you can go directly to any specific one to solve your specific API needs.

It is also built to work as a future reference so you can come back and see exactly what you need.

## Run the code

    putAll(multimap);
  }

  /**
   * {@inheritDoc}
   *
   * <p>Creates an empty {@code HashSet} for a collection of values for one key.
   *
   * @return a new {@code HashSet} containing a collection of values for one key
   */
  @Override
  Set<V> createCollection() {
    return Platform.<V>newHashSetWithExpectedSize(expectedValuesPerKey);
  }

  /**

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *