```

#### Unpacking a `dict` { #unpacking-a-dict }

If we take a `dict` like `user_dict` and pass it to a function (or class) with `**user_dict`, Python will "unpack" it. It will pass the keys and values of the `user_dict` directly as key-value arguments.

So, continuing with the `user_dict` from above, writing:

```Python
UserInDB(**user_dict)
```

would result in something equivalent to:

```Python
UserInDB(
    username="john",

            result.setCrawlingInfoId(DfTypeUtil.toString(source.get("crawlingInfoId")));
            result.setCreatedTime(DfTypeUtil.toLong(source.get("createdTime")));
            result.setKey(DfTypeUtil.toString(source.get("key")));
            result.setValue(DfTypeUtil.toString(source.get("value")));
            return updateEntity(source, result);
        } catch (InstantiationException | IllegalAccessException e) {

                    MojoNotFoundException, InvalidPluginDescriptorException {
        /*
         * Initialize mapping from lifecycle phase to bound mojos. The key set of this map denotes the phases the caller
         * is interested in, i.e. all phases up to and including the specified phase.
         */

        Map<String, Map<PhaseId, List<MojoExecution>>> mappings =

  if (entry != GetFactories().end()) {
    default_factory = GetFactories().find(name)->second;
    return absl::OkStatus();
  }
  string msg = absl::StrCat(
      "No tracing engine factory has been registered with the key '", name,
      "' (available: ");
  // Ensure deterministic (sorted) order in the error message
  std::set<string> factories_sorted;
  for (const auto& factory : GetFactories())
    factories_sorted.insert(factory.first);

        },
        {
            "url": "http://example.com/dave.jpg",
            "name": "The Baz"
        }
    ]
}
```

/// info

Notice how the `images` key now has a list of image objects.

///

## Deeply nested models { #deeply-nested-models }

You can define arbitrarily deeply nested models:

    }

    /**
     * Request a new durable handle
     * @param path the file path
     * @param type the handle type
     * @param timeout the timeout in milliseconds
     * @param leaseKey the associated lease key (can be null)
     * @return the handle GUID
     */
    public HandleGuid requestDurableHandle(String path, HandleType type, long timeout, Smb2LeaseKey leaseKey) {
        HandleGuid guid = new HandleGuid();

				tmpRec := input.Clone(nil)
				if err = tmpRec.Replace(val); err != nil {
					return nil, err
				}
				recs[i] = &tmpRec
			}
			return recs, nil

		default:
			kvs = jstream.KVS{jstream.KV{Key: "_1", Value: v}}
		}

		if err = input.Replace(kvs); err != nil {
			return nil, err
		}

		return []*Record{&input}, nil
	case simdjson.Object:

         *
         * @param defaultField the default field name
         * @param field the field name to split
         * @return a Pair containing the field name and extension key
         */
        protected Pair<String, String> splitField(final String defaultField, final String field) {
            final int indexOf = field.indexOf(':');
            if (indexOf < 0) {

這裡有個小技巧偶爾很好用，不過你大概不常需要。

如果你想要：

* 不用 `Query`、也不給預設值就宣告查詢參數 `q`
* 使用 `Path` 宣告路徑參數 `item_id`
* 讓它們的順序不同
* 不使用 `Annotated`

…Python 有個小語法可以做到。

在函式的參數列表最前面放一個 `*`。

Python 不會對這個 `*` 做任何事，但它會知道後續的所有參數都必須以關鍵字引數（key-value pairs）方式呼叫，也就是所謂的 <abbr title="源自：K-ey W-ord Arg-uments - 關鍵字參數"><code>kwargs</code></abbr>。即便它們沒有預設值也一樣。

{* ../../docs_src/path_params_numeric_validations/tutorial003_py310.py hl[7] *}

  }
}
```

- `aws:UserAgent` - This value is a string that contains information about the requester's client application. This string is generated by the client and can be unreliable. You can only use this context key from `mc` or other MinIO SDKs which standardize the User-Agent string.