```Python hl_lines="6"
{!../../docs_src/first_steps/tutorial001.py!}
```

`@app.get("/")` nói **FastAPI** rằng hàm bên dưới có trách nhiệm xử lí request tới:

* đường dẫn `/`
* sử dụng một <abbr title="an HTTP GET method">toán tử<code>get</code></abbr>

/// info | Thông tin về "`@decorator`"

Cú pháp `@something` trong Python được gọi là một "decorator".

   *
   * <p>If {@code !range.contains(k)}, {@link #get(Comparable) get(k)} will return the same result
   * before and after a call to {@code remove(range)}. If {@code range.contains(k)}, then after a
   * call to {@code remove(range)}, {@code get(k)} will return {@code null}.
   */
  void remove(Range<K> range);

  /**

client = TestClient(app)


def test_redirect_status_code():
    response = client.get("/pydantic", follow_redirects=False)
    assert response.status_code == 302
    assert response.headers["location"] == "https://docs.pydantic.dev/"


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {

from docs_src.path_operation_advanced_configuration.tutorial005 import app

client = TestClient(app)


def test_get():
    response = client.get("/items/")
    assert response.status_code == 200, response.text


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",

        List<Integer> copy = new ArrayList<>(input);
        sort(copy);
        dummy += copy.get(0);
      }
    } else {
      for (int i = 0; i < reps; i++) {
        List<Integer> copy = new ArrayList<>(input);
        sort(copy);
        dummy += ImmutableList.copyOf(copy).get(0);
      }
    }
    return dummy;
  }

  @Benchmark
  int ordering(int reps) {
    int dummy = 0;

        buildFinished {
            if ((cacheMissInBuildLogic as AtomicBoolean).get() || (cacheMissInMainBuild as AtomicBoolean).get()) {
                tag("CACHE_MISS")
            }
        }
    }
}

fun buildCacheEnabled() = gradle.startParameter.isBuildCacheEnabled

  val osgiApi = project.configurations.getByName(osgiApiConfigurationName)
  val kotlinOsgi =
    extensions.getByType(VersionCatalogsExtension::class.java).named("libs")
      .findLibrary("kotlin.stdlib.osgi").get().get()

  project.dependencies {
    osgiApi(kotlinOsgi)
  }

  val jarTask = tasks.getByName<Jar>(jarTaskName)
  val bundleExtension =
    jarTask.extensions.findByType() ?: jarTask.extensions.create(

   * create, cache and return" pattern. For further improvements, use {@link LoadingCache} and its
   * {@link LoadingCache#get(Object) get(K)} method instead of this one.
   *
   * <p>Among the improvements that this method and {@code LoadingCache.get(K)} both provide are:
   *
   * <ul>
   *   <li>{@linkplain LoadingCache#get(Object) awaiting the result of a pending load} rather than
   *       starting a redundant one

func getReqAccessKeyV4(r *http.Request, region string, stype serviceType) (auth.Credentials, bool, APIErrorCode) {
	ch, s3Err := parseCredentialHeader("Credential="+r.Form.Get(xhttp.AmzCredential), region, stype)
	if s3Err != ErrNone {
		// Strip off the Algorithm prefix.
		v4Auth := strings.TrimPrefix(r.Header.Get("Authorization"), signV4Algorithm)
		authFields := strings.Split(strings.TrimSpace(v4Auth), ",")
		if len(authFields) != 3 {

from fastapi.testclient import TestClient

from docs_src.advanced_middleware.tutorial003 import app


@app.get("/large")
async def large():
    return PlainTextResponse("x" * 4000, status_code=200)


client = TestClient(app)


def test_middleware():
    response = client.get("/large", headers={"accept-encoding": "gzip"})
    assert response.status_code == 200, response.text
    assert response.text == "x" * 4000