@Test
    public void test_unicode_base64_encoding() {
        // Test that unicode strings are properly encoded/decoded
        String unicodeString = "日本語テスト";
        String encoded = BaseEncoding.base64().encode(unicodeString.getBytes(StandardCharsets.UTF_8));
        String decoded = new String(BaseEncoding.base64().decode(encoded), StandardCharsets.UTF_8);

        assertEquals(unicodeString, decoded);
    }

    @Test

**FastAPI** will make sure to read that data from the right place instead of JSON.

/// note | Technical Details

Data from forms is normally encoded using the "media type" `application/x-www-form-urlencoded`.

But when the form includes files, it is encoded as `multipart/form-data`. You'll read about handling files in the next chapter.

// ContainsAny reports whether any of the UTF-8-encoded code points in chars are within b.
func ContainsAny(b []byte, chars string) bool {
	return IndexAny(b, chars) >= 0
}

// ContainsRune reports whether the rune is contained in the UTF-8-encoded byte slice b.
func ContainsRune(b []byte, r rune) bool {
	return IndexRune(b, r) >= 0
}

// ContainsFunc reports whether any of the UTF-8-encoded code points r within b satisfy f(r).

  /**
   * Exception indicating invalid base-encoded input encountered while decoding.
   *
   * @author Louis Wasserman
   * @since 15.0
   */
  public static final class DecodingException extends IOException {
    DecodingException(@Nullable String message) {
      super(message);
    }
  }

  /** Encodes the specified byte array, and returns the encoded {@code String}. */
  public String encode(byte[] bytes) {

JSON can only contain UTF-8 encoded strings, so it can't contain raw bytes.

Base64 can encode binary data in strings, but to do it, it needs to use more characters than the original binary data, so it would normally be less efficient than regular files.

**FastAPI** will make sure to read that data from the right place instead of JSON.

/// note | Technical Details

Data from forms is normally encoded using the "media type" `application/x-www-form-urlencoded` when it doesn't include files.

But when the form includes files, it is encoded as `multipart/form-data`. If you use `File`, **FastAPI** will know it has to get the files from the correct part of the body.

Import `EventSourceResponse` from `fastapi.sse`:

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[1:25] hl[4,22] *}

Each yielded item is encoded as JSON and sent in the `data:` field of an SSE event.

If you declare the return type as `AsyncIterable[Item]`, FastAPI will use it to **validate**, **document**, and **serialize** the data using Pydantic.

    `response_class=EventSourceResponse`, each `ServerSentEvent` is encoded
    into the [SSE wire format](https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream)
    (`text/event-stream`).

    If you yield a plain object (dict, Pydantic model, etc.) instead, it is
    automatically JSON-encoded and sent as the `data:` field.

/// warning

You can declare multiple `File` and `Form` parameters in a *path operation*, but you can't also declare `Body` fields that you expect to receive as JSON, as the request will have the body encoded using `multipart/form-data` instead of `application/json`.

This is not a limitation of **FastAPI**, it's part of the HTTP protocol.

///

## Recap { #recap }

     * HTTP/1.1 200 OK
     * 3
     * Content-Type: image/png
     * Content-Length: 100
     * Cache-Control: max-age=600
     *
     * AES_256_WITH_MD5
     * 2
     * base64-encoded peerCertificate[0]
     * base64-encoded peerCertificate[1]
     * -1
     * TLSv1.2
     * ```
     *
     * The file is newline separated. The first two lines are the URL and the request method. Next