*/
internal sealed class Tags {
  /**
   * Returns a tags instance that maps [key] to [value]. If [value] is null, this returns a tags
   * instance that does not have any mapping for [key].
   */
  abstract fun <T : Any> plus(
    key: KClass<T>,
    value: T?,
  ): Tags

  abstract operator fun <T : Any> get(key: KClass<T>): T?
}

/** An empty tags. This is always the tail of a [LinkedTags] chain. */

            "limit": 10,
            "offset": 5,
            "order_by": "updated_at",
            "tags": ["tag1", "tag2"],
        },
    )
    assert response.status_code == 200
    assert response.json() == {
        "limit": 10,
        "offset": 5,
        "order_by": "updated_at",
        "tags": ["tag1", "tag2"],
    }


def test_query_param_model_defaults(client: TestClient):

        "price": 50.2,
        "tax": 10.5,
        "tags": [],
    }


def test_patch_all(client: TestClient):
    response = client.patch(
        "/items/foo",
        json={
            "name": "Fooz",
            "description": "Item description",
            "price": 3,
            "tax": 10.5,
            "tags": ["tag1", "tag2"],
        },
    )
    assert response.json() == {

            "limit": 10,
            "offset": 5,
            "order_by": "updated_at",
            "tags": ["tag1", "tag2"],
        },
    )
    assert response.status_code == 200
    assert response.json() == {
        "limit": 10,
        "offset": 5,
        "order_by": "updated_at",
        "tags": ["tag1", "tag2"],
    }


def test_query_param_model_defaults(client: TestClient):

        assertNotNull(dataMap);
        assertTrue(dataMap.get("tags") instanceof List);
        @SuppressWarnings("unchecked")
        List<String> tags = (List<String>) dataMap.get("tags");
        assertEquals(3, tags.size());
        assertEquals("tag1", tags.get(0));
        assertEquals("tag2", tags.get(1));
        assertEquals("tag3", tags.get(2));
    }

        .plus(Boolean::class, null)
    assertThat(tags).isEqualTo(EmptyTags)
    assertThat(tags.toString()).isEqualTo("{}")
  }

  @Test
  fun removeAbsentFromEmpty() {
    val tags = EmptyTags.plus(String::class, null)
    assertThat(tags).isEqualTo(EmptyTags)
    assertThat(tags.toString()).isEqualTo("{}")
  }

  @Test
  fun removeAbsentFromNonEmpty() {
    val tags =
      EmptyTags

                                    "required": ["name", "tags"],
                                    "type": "object",
                                    "properties": {
                                        "name": {"title": "Name", "type": "string"},
                                        "tags": {
                                            "title": "Tags",
                                            "type": "array",

/// tip

You don't have to add metadata for all the tags that you use.

///

### Use your tags { #use-your-tags }

Use the `tags` parameter with your *path operations* (and `APIRouter`s) to assign them to different tags:

{* ../../docs_src/metadata/tutorial004_py39.py hl[21,26] *}

/// info

Read more about tags in [Path Operation Configuration](path-operation-configuration.md#tags){.internal-link target=_blank}.

///

from enum import Enum

from fastapi import FastAPI

app = FastAPI()


class Tags(Enum):
    items = "items"
    users = "users"


@app.get("/items/", tags=[Tags.items])
async def get_items():
    return ["Portal gun", "Plumbus"]


@app.get("/users/", tags=[Tags.users])
async def read_users():

<%@taglib prefix="c" uri="jakarta.tags.core"%><%--
 --%><%@taglib prefix="fmt" uri="jakarta.tags.fmt"%><%--
 --%><%@taglib prefix="fn" uri="jakarta.tags.functions" %><%--
 --%><%@taglib prefix="la" uri="http://lastaflute.org/latags" %><%--
 --%><%@taglib prefix="f" uri="http://lastaflute.org/functions" %><%--
 --%><%@taglib prefix="fe" uri="fess.tags.functions" %><%--