### 嵌套类型

有些容器数据结构可以包含其他的值，比如 `dict`、`list`、`set` 和 `tuple`。它们内部的值也会拥有自己的类型。

你可以使用 Python 的 `typing` 标准库来声明这些类型以及子类型。

它专门用来支持这些类型提示。

#### 列表

例如，让我们来定义一个由 `str` 组成的 `list` 变量。

从 `typing` 模块导入 `List`（注意是大写的 `L`）：

{* ../../docs_src/python_types/tutorial006.py hl[1] *}


同样以冒号（`:`）来声明这个变量。

输入 `List` 作为类型。

由于列表是带有"子类型"的类型，所以我们把子类型放在方括号中：

	}
	in.macros[name] = &Macro{
		name:   name,
		args:   args,
		tokens: tokens,
	}
}

// macroDefinition returns the list of formals and the tokens of the definition.
// The argument list is nil for no parens on the definition; otherwise a list of
// formal argument names.
func (in *Input) macroDefinition(name string) ([]string, []Token) {
	prevCol := in.Stack.Col()
	tok := in.Stack.Next()

    url: HttpUrl
    name: str


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()
    images: Union[list[Image], None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.lang.StringUtil;

    public ColumnInfo columnUpdatedBy() {
        return _columnUpdatedBy;
    }

    public ColumnInfo columnUpdatedTime() {
        return _columnUpdatedTime;
    }

    protected List<ColumnInfo> ccil() {
        List<ColumnInfo> ls = newArrayList();
        ls.add(columnCreatedBy());
        ls.add(columnCreatedTime());
        ls.add(columnSuggestWord());
        ls.add(columnTargetLabel());

    public ColumnInfo columnUpdatedTime() {
        return _columnUpdatedTime;
    }

    public ColumnInfo columnUrlExpr() {
        return _columnUrlExpr;
    }

    protected List<ColumnInfo> ccil() {
        List<ColumnInfo> ls = newArrayList();
        ls.add(columnBoostExpr());
        ls.add(columnCreatedBy());
        ls.add(columnCreatedTime());
        ls.add(columnSortOrder());

    private final Logger logger = LoggerFactory.getLogger(getClass());
    private final RepositorySystem repoSystem;
    private final List<RepositorySessionDecorator> decorators;

    @Inject
    public DefaultProjectDependenciesResolver(
            RepositorySystem repoSystem, List<RepositorySessionDecorator> decorators) {
        this.repoSystem = repoSystem;
        this.decorators = decorators;
    }

    @Override

        private final LocalRepository localRepo;

        private final List<RemoteRepository> repositories;

        private final Set<String> collect;

        private final Set<String> resolve;

        private boolean aggregating;

        private final int hashCode;

        public CacheKey(
                MavenProject project,
                List<RemoteRepository> repositories,

	if err != nil {
		h = host
	}
	ip := net.ParseIP(h)
	return ip.To16() != nil && ip.To4() == nil
}

// strip api endpoints list with standard ports such as
// port "80" and "443" before displaying on the startup
// banner.  Returns a new list of API endpoints.
func stripStandardPorts(apiEndpoints []string, host string) (newAPIEndpoints []string) {
	if len(apiEndpoints) == 1 {
		return apiEndpoints
	}

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.maven.artifact.metadata.ArtifactMetadata;
import org.apache.maven.artifact.repository.ArtifactRepository;
import org.apache.maven.artifact.repository.ArtifactRepositoryPolicy;