*/
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. */

		t.Fatalf("Blog should has three tags after Append")
	}

	if count := DB.Model(&blog).Association("Tags").Count(); count != 3 {
		t.Fatalf("Blog should has 3 tags after Append, got %v", count)
	}

	var tags []Tag
	DB.Model(&blog).Association("Tags").Find(&tags)
	if !compareTags(tags, []string{"tag1", "tag2", "tag3"}) {
		t.Fatalf("Should find 3 tags")
	}

	var blog1 Blog
	DB.Preload("Tags").Find(&blog1)

	defer r.Unlock()
	// Search of tag key already exists in tags
	var updated bool
	for _, tag := range r.tags {
		if tag.Key == key {
			tag.Val = val
			updated = true
			break
		}
	}
	if !updated {
		// Append to the end of tags list
		r.tags = append(r.tags, KeyVal{key, val})
	}
	return r
}

// GetTags - returns the user defined tags
func (r *ReqInfo) GetTags() []KeyVal {
	if r == nil {

        .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

        List<String> fields = new ArrayList<>();
        fields.add("field1");
        List<String> tags = new ArrayList<>();
        tags.add("tag1");
        List<String> roles = new ArrayList<>();
        roles.add("role1");

        elevateWord = new ElevateWord(word, boost, readings, fields, tags, roles);

        // Check that we get the same references
        assertTrue(readings == elevateWord.getReadings());

                                    "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}.

///

            "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):

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():

        "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() == {