return delta;
        }
        // atomic is now non-null; fall through
      }

      while (true) {
        long oldValue = atomic.get();
        if (oldValue == 0L) {
          // don't compareAndSet a zero
          if (map.replace(key, atomic, new AtomicLong(delta))) {
            return delta;
          }
          // atomic replaced
          continue outer;
        }

And if you update that local FastAPI source code when you run that Python file again, it will use the fresh version of FastAPI you just edited.

That way, you don't have to "install" your local version to be able to test every change.

/// note | Technical Details

This only happens when you install using `uv sync --extra all` instead of running `pip install fastapi` directly.

  val knownFailures =
    setOf(
      // OkHttp rejects empty labels.
      "x..xn--zca",
      "x..ß",
      // OkHttp rejects labels longer than 63 code points, the web platform tests don't.
      "x01234567890123456789012345678901234567890123456789012345678901x.xn--zca",
      "x01234567890123456789012345678901234567890123456789012345678901x.ß",
      "x01234567890123456789012345678901234567890123456789012345678901x",

  private final ImmutableMap<C, ImmutableMap<R, V>> columnMap;

  @SuppressWarnings("Immutable") // We don't modify this after construction.
  private final int[] rowCounts;

  @SuppressWarnings("Immutable") // We don't modify this after construction.
  private final int[] columnCounts;

  @SuppressWarnings("Immutable") // We don't modify this after construction.
  private final @Nullable V[][] values;

                String key = parts[0];
                String[] keyParts = key.split("\\.");
                String value = parts[1];

                // We don't need to explicitly define a console appender because the
                // "rolling" appender will become a console appender. We also don't
                // carry over "*_old" appenders
                if (keyParts[1].equals("console") || keyParts[1].endsWith("_old")) {

        // nothing to do, we must have been cancelled, don't bother inspecting the future.
        return;
      }
      Object valueToSet = getFutureValue(future);
      if (casValue(owner, this, valueToSet)) {
        complete(
            owner,
            /*
             * Interruption doesn't propagate through a DelegatingToFuture chain (see
             * getFutureValue), so don't invoke interruptTask.
             */

// as an error to be reported.
//
// passes NOATIME flag for reads on Unix systems to avoid atime updates.
func ReadFile(name string) ([]byte, error) {
	// Don't wrap with un-needed buffer.
	// Don't use os.ReadFile, since it doesn't pass NO_ATIME when present.
	f, err := OsOpenFile(name, readMode, 0o666)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	st, err := f.Stat()

    <property name="id" value="SnippetLength" />
    <property name="max" value="76" />
  </module>

  <!-- Its our official line length! See checkstyle_suppressions.xml for the files that don't pass this. For now we
    suppress the check there but enforce it everywhere else. This prevents the list from getting longer even if it is
    unfair. -->
  <module name="LineLength">
    <property name="max" value="140" />

			return false
		}
		return versions[i].ModTime.After(versions[j].ModTime)
	})

	for i, fi := range fivs.Versions {
		if fi.VersionID != versions[i].VersionID {
			t.Fatalf("getFileInfoVersions: versions don't match at %d, version id expected %s but got %s", i, fi.VersionID, versions[i].VersionID)
		}
		if fi.NumVersions != len(fivs.Versions) {

to introduce it.'

  `I don't like the look of it at all,' said the King:
`however, it may kiss my hand if it likes.'

  `I'd rather not,' the Cat remarked.

  `Don't be impertinent,' said the King, `and don't look at me
like that!'  He got behind Alice as he spoke.

  `A cat may look at a king,' said Alice.  `I've read that in
some book, but I don't remember where.'