}
      }

      // There's another part. Parse its headers and return it.
      val headers = HeadersReader(source).readHeaders()
      val partSource = PartSource()
      currentPart = partSource
      return Part(headers, partSource.buffer())
    }

    /** A single part in the stream. It is an error to read this after calling [nextPart]. */

{* ../../docs_src/middleware/tutorial001_py39.py hl[8:9,11,14] *}

/// tip

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the `X-` prefix</a>.

    assertThat(response.body.string()).isEqualTo("a")
    assertThat(eventRecorder.recordedEventTypes())
      .containsExactly(CallStart::class, CallEnd::class)
  }

  /** Response headers start, then the entire request body, then response headers end.  */
  @Test
  fun expectContinueStartsResponseHeadersEarly() {
    server.enqueue(
      MockResponse
        .Builder()
        .add100Continue()
        .build(),

        Doc(
            """
            Automatically convert underscores to hyphens in the parameter field name.

            Read more about it in the
            [FastAPI docs for Header Parameters](https://fastapi.tiangolo.com/tutorial/header-params/#automatic-conversion)
            """
        ),
    ] = True,
    title: Annotated[
        Optional[str],
        Doc(
            """

                logger.debug("Failed to retrieval a cache.", e);
            }
            return new XPathAPI();
        }
    }

    /**
     * Returns the header for the result data.
     * @return The result data header.
     */
    protected String getResultDataHeader() {
        // TODO support other type
        return "<?xml version=\"1.0\"?>\n<doc>\n";
    }

    /**

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.GenericDeclaration;
import java.lang.reflect.Type;

"src/compress/gzip/testdata/issue6550.gz.base64", "src/compress/lzw/", "src/compress/lzw/reader.go", "src/compress/lzw/reader_test.go", "src/compress/lzw/writer.go", "src/compress/lzw/writer_test.go", "src/compress/testdata/", "src/compress/testdata/e.txt", "src/compress/testdata/gettysburg.txt", "src/compress/testdata/pi.txt", "src/compress/zlib/", "src/compress/zlib/example_test.go", "src/compress/zlib/reader.go", "src/compress/zlib/reader_test.go", "src/compress/zlib/writer.go", "src/compress/z...

So we put them in their own `dependencies` module (`app/dependencies.py`).

We will now use a simple dependency to read a custom `X-Token` header:

{* ../../docs_src/bigger_applications/app_an_py39/dependencies.py hl[3,6:8] title["app/dependencies.py"] *}

/// tip

We are using an invented header to simplify this example.

## Usando `Depends` y otros { #using-depends-and-others }

En endpoints de WebSocket puedes importar desde `fastapi` y usar:

* `Depends`
* `Security`
* `Cookie`
* `Header`
* `Path`
* `Query`

Funcionan de la misma manera que para otros endpoints de FastAPI/*path operations*:

{* ../../docs_src/websockets/tutorial002_an_py310.py hl[68:69,82] *}

/// info | Información

        }
        byte[] nameBytes = "bob".getBytes(StandardCharsets.US_ASCII);

        return Stream.of(
                // Too short for TOK_ID + MECH_OID_LEN
                Arguments.of("too short header", new byte[] { 0x04, 0x01, 0x00 }, IllegalArgumentException.class),

                // Wrong TOK_ID
                Arguments.of("wrong TOK_ID", new byte[] { 0x00, 0x02, 0x00, 0x01 }, IllegalArgumentException.class),