"properties": {
                        "loc": {
                            "title": "Location",
                            "type": "array",
                            "items": {
                                "anyOf": [{"type": "string"}, {"type": "integer"}]
                            },
                        },
                        "msg": {"title": "Message", "type": "string"},

    # Update the viewport manually
    context = browser.new_context(viewport={"width": 960, "height": 1080})
    page = context.new_page()
    page.goto("http://localhost:8000/docs")
    page.get_by_text("GET/items/Read Items").click()
    page.get_by_role("tab", name="Schema").click()
    page.get_by_label("Schema").get_by_role("button", name="Expand all").click()
    # Manually add the screenshot
    page.screenshot(

    // Each group is a List of items, each item has a list of factory args.
    final List<List<List<Object>>> argGroups = Lists.newArrayList();
    argGroups.add(ImmutableList.of(args, equalArgs));
    EqualsTester tester =
        new EqualsTester(
            new ItemReporter() {
              @Override
              String reportItem(Item<?> item) {

	}
	if err := decoder.Err(); err != nil {
		t.Fatalf("decoder error: %s", err)
	}
	if kvcounter != 0 {
		t.Fatalf("expected 0 keyvalue items, got %d", kvcounter)
	}
	if counter != 15 {
		t.Fatalf("expected 15 items, got %d", counter)
	}

	// test at depth level 1 w/ emitKV
	counter = 0
	kvcounter = 0
	decoder = NewDecoder(mkReader(body), 1).EmitKV()

constraints.Future.message      = {item} must be in the future.
constraints.Max.message         = {item} must be less than or equal to {value}.
constraints.Min.message         = {item} must be greater than or equal to {value}.
constraints.NotNull.message     = {item} may not be null.
constraints.Null.message        = {item} must be null.
constraints.Past.message        = {item} must be in the past.
constraints.Pattern.message     = {item} must match "{regexp}".

constraints.Future.message      = {item} must be in the future.
constraints.Max.message         = {item} must be less than or equal to {value}.
constraints.Min.message         = {item} must be greater than or equal to {value}.
constraints.NotNull.message     = {item} may not be null.
constraints.Null.message        = {item} must be null.
constraints.Past.message        = {item} must be in the past.
constraints.Pattern.message     = {item} must match "{regexp}".

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：

```Python hl_lines="4"
{!../../docs_src/python_types/tutorial006.py!}
```

这表示："变量 `items` 是一个 `list`，并且这个列表里的每一个元素都是 `str`"。

这样，即使在处理列表中的元素时，你的编辑器也可以提供支持。

没有类型，几乎是不可能实现下面这样：

<img src="https://fastapi.tiangolo.com/img/python-types/image05.png">

注意，变量 `item` 是列表 `items` 中的元素之一。

而且，编辑器仍然知道它是一个 `str`，并为此提供了支持。

#### 元组和集合

声明 `tuple` 和 `set` 的方法也是一样的：

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: str = Query(default=..., min_length=3)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: str = Query(default=..., min_length=3)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/")
async def read_items(q: Union[str, None] = None):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})