if !httpWriter.HasWritten() {
			// write error response only if no data or headers has been written to client yet
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}
		return
	}

	if err = httpWriter.Close(); err != nil {
		if !httpWriter.HasWritten() { // write error response only if no data or headers has been written to client yet
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)

			// Make sure we remove any existing headers before
			// proxying the request to another node.
			for k := range w.Header() {
				w.Header().Del(k)
			}
			globalForwarder.ServeHTTP(w, r)
			return
		}
		h.ServeHTTP(w, r)
	})
}

// addCustomHeadersMiddleware adds various HTTP(S) response headers.
// Security Headers enable various security protections behaviors in the client's browser.

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

import com.google.common.annotations.GwtCompatible;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.testing.features.MapFeature;
import java.util.List;
import org.junit.Ignore;

/**
 * Testers for {@link ListMultimap#putAll(Object, Iterable)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

import com.google.common.annotations.GwtCompatible;

			fieldDelimiter:  ",",
			sendErr:         nil,
			header:          true,
			wantColumns:     []string{"header1", "header2", "header3"},
			wantFields:      "ok1,ok2,ok3\n" + `a word,"b"""` + "\n",
			wantErr:         io.EOF,
		},
		{
			// This works since LazyQuotes is true:
			file:            "invalid-badstartline.csv",
			recordDelimiter: "\n",
			fieldDelimiter:  ",",
			sendErr:         nil,

public abstract class CorsHandler {

    protected static final String ACCESS_CONTROL_ALLOW_ORIGIN = "Access-Control-Allow-Origin";

    protected static final String ACCESS_CONTROL_ALLOW_HEADERS = "Access-Control-Allow-Headers";

    protected static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";

    protected static final String ACCESS_CONTROL_ALLOW_PRIVATE_NETWORK = "Access-Control-Allow-Private-Network";

          call: Call,
          response: Response,
        ) {
          response.use {
            if (!response.isSuccessful) throw IOException("Unexpected code $response")

            for ((name, value) in response.headers) {
              println("$name: $value")
            }

            println(response.body.string())
          }
        }
      },
    )
  }
}

fun main() {
  AsynchronousGet().run()

def test_get_redirect():
    response = client.get("/portal", params={"teleport": True}, follow_redirects=False)
    assert response.status_code == 307, response.text
    assert response.headers["location"] == "https://www.youtube.com/watch?v=dQw4w9WgXcQ"


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {

///

## Add custom headers

There are some situations in where it's useful to be able to add custom headers to the HTTP error. For example, for some types of security.

You probably won't need to use it directly in your code.

But in case you needed it for an advanced scenario, you can add custom headers:

```Python hl_lines="14"
{!../../docs_src/handling_errors/tutorial002.py!}