private void readObject(ObjectInputStream stream) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  /*
   * This class is used to serialize ImmutableEnumSet instances.
   */
  @J2ktIncompatible // serialization
  private static final class EnumSerializedForm<E extends Enum<E>> implements Serializable {
    final EnumSet<E> delegate;

        DictionaryExpiredException original = new DictionaryExpiredException();

        // Serialize
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(baos);
        oos.writeObject(original);
        oos.close();

        // Deserialize
        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());

import org.jspecify.annotations.Nullable;

/**
 * Provides static methods for serializing collection classes.
 *
 * <p>This class assists the implementation of collection classes. Do not use this class to
 * serialize collections that are defined elsewhere.
 *
 * @author Jared Levy
 */
@GwtIncompatible
@J2ktIncompatible
final class Serialization {
  private Serialization() {}

  /**

        try {
            toolchainsWriter.write(stringWriter, null, toolchains);
        } catch (IOException e) {
            throw new IllegalStateException("Failed to serialize toolchains to memory", e);
        }

        String serializedToolchains = stringWriter.toString();

        RegexBasedInterpolator interpolator = new RegexBasedInterpolator();

        try {

		} else {
			versions = append(versions, fi)
			allVersionIDs = append(allVersionIDs, fi.VersionID)
		}
	}
	buf, err := xl.AppendTo(nil)
	if err != nil {
		t.Fatalf("Failed to serialize xlmeta %v", err)
	}
	fivs, err := getFileInfoVersions(buf, basefi.Volume, basefi.Name, false)
	if err != nil {
		t.Fatalf("getFileInfoVersions failed: %v", err)
	}
	chkNumVersions := func(fis []FileInfo) bool {

import org.jspecify.annotations.Nullable;

/**
 * Provides static methods for serializing collection classes.
 *
 * <p>This class assists the implementation of collection classes. Do not use this class to
 * serialize collections that are defined elsewhere.
 *
 * @author Jared Levy
 */
@GwtIncompatible
@J2ktIncompatible
final class Serialization {
  private Serialization() {}

  /**

        StringWriter writer = new StringWriter(1024 * 4);

        try {
            settingsWriter.write(writer, null, settings);
        } catch (IOException e) {
            throw new IllegalStateException("Failed to serialize settings to memory", e);
        }

        String serializedSettings = writer.toString();

        RegexBasedInterpolator interpolator = new RegexBasedInterpolator();

### No Annotation { #no-annotation }

You don't really need to declare the return type annotation for streaming binary data.

As FastAPI will not try to convert the data to JSON with Pydantic or serialize it in any way, in this case, the type annotation is only for your editor and tools to use, it won't be used by FastAPI.

{* ../../docs_src/stream_data/tutorial001_py310.py ln[32:35] hl[33] *}

            raise ResponseValidationError(
                errors=errors,
                body=response_content,
                endpoint_ctx=ctx,
            )
        serializer = field.serialize_json if dump_json else field.serialize
        return serializer(
            value,
            include=include,
            exclude=exclude,
            by_alias=by_alias,
            exclude_unset=exclude_unset,

```

</div>

Then go to the `/docs` UI, you will see that **FastAPI** is using these **models** to **document** the API, and it will use them to **serialize** and **validate** the data too.

<div class="screenshot">
<img src="/img/tutorial/sql-databases/image01.png">
</div>

## Update the App with Multiple Models { #update-the-app-with-multiple-models }