If you just don't know, use normal `def`.

---

**Note**: You can mix `def` and `async def` in your *path operation functions* as much as you need and define each one using the best option for you. FastAPI will do the right thing with them.

Anyway, in any of the cases above, FastAPI will still work asynchronously and be extremely fast.

But by following the steps above, it will be able to do some performance optimizations.

</div>

## Cấu hình Trình soạn thảo của bạn

Nếu bạn sử dụng một trình soạn thảo, hãy đảm bảo bạn cấu hình nó để sử dụng cùng môi trường ảo mà bạn đã tạo (trình soạn thảo sẽ tự động phát hiện môi trường ảo) để bạn có thể nhận được tính năng tự động hoàn thành câu lệnh (autocomplete) và in lỗi trực tiếp trong trình soạn thảo (inline errors).

Ví dụ:

   * `new Integer` (as we do) instead of `Integer.valueOf`. However, under J2KT, `new Integer`
   * gets translated back to `Integer.valueOf` because that is the only thing J2KT can support. And
   * anyway, it's nice to avoid `Integer.valueOf` because the Android toolchain optimizes multiple
   * `Integer.valueOf` calls into one! So we stick with the deprecated `Integer` constructor.
   */

   * `new Integer` (as we do) instead of `Integer.valueOf`. However, under J2KT, `new Integer`
   * gets translated back to `Integer.valueOf` because that is the only thing J2KT can support. And
   * anyway, it's nice to avoid `Integer.valueOf` because the Android toolchain optimizes multiple
   * `Integer.valueOf` calls into one! So we stick with the deprecated `Integer` constructor.
   */

import java.nio.file.attribute.PosixFileAttributes;
import java.util.Arrays;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit tests for {@link FileBackedOutputStream}.
 *
 * <p>For a tiny bit more testing, see {@link FileBackedOutputStreamAndroidIncompatibleTest}.
 *
 * @author Chris Nokleberg
 */
@NullUnmarked
public class FileBackedOutputStreamTest extends IoTestCase {

But Facebook login doesn't support OpenID Connect. It has its own flavor of OAuth2.

### OpenID (not "OpenID Connect") { #openid-not-openid-connect }

There was also an "OpenID" specification. That tried to solve the same thing as **OpenID Connect**, but was not based on OAuth2.

So, it was a complete additional system.

It is not very popular or used nowadays.

## OpenAPI { #openapi }

 * attempting to add new elements onto the queue and it is full. This queue orders elements FIFO
 * (first-in-first-out). This data structure is logically equivalent to a circular buffer (i.e.,
 * cyclic buffer or ring buffer).
 *
 * <p>An evicting queue must be configured with a maximum size. Each time an element is added to a
 * full queue, the queue automatically removes its head element. This is different from conventional

            for (ChannelInfo channel : channelGroup.getChannels()) {
                try {
                    // Simplified health check - in real implementation would ping the channel
                    boolean isHealthy = checkChannelHealth(channel);
                    channel.setHealthy(isHealthy);

                    if (!isHealthy) {

    when pooled connections are evicted).

    If you have a configured ping interval, you should confirm that it is long
    enough for a roundtrip from client to server. If your ping interval is too
    short, slow connections may be misinterpreted as failed connections. A ping
    interval of 30 seconds is reasonable for most use cases.

 * (like 0030..0039).
 *
 * The second element on each line is a mapping type, like `valid` or `mapped`.
 *
 * For lines that contain a mapping target, the next thing is a sequence of hex code points (like
 * 0031 2044 0034).
 *
 * All other data is ignored.
 */
fun BufferedSource.readPlainTextIdnaMappingTable(): SimpleIdnaMappingTable {
  val mappedTo = Buffer()