// be an empty string if no device was explicitly requested, but will
  // otherwise be the name of this custom device. Ops are placed onto a custom
  // device if any of their inputs are on that custom device, but custom devices
  // are free to set a bad status in order to require explicit placement.
  void (*execute)(const TFE_Op* op, int* num_outputs,

///

## Returning a custom `Response`

The example above shows all the parts you need, but it's not very useful yet, as you could have just returned the `item` directly, and **FastAPI** would put it in a `JSONResponse` for you, converting it to a `dict`, etc. All that by default.

Now, let's see how you could use that to return a custom response.

    metadata = context.config.metadata
    # Get custom config for the current package, from the env var
    config: Dict[str, Any] = context.config.data["tool"]["tiangolo"][
        "_internal-slim-build"
    ]["packages"].get(TIANGOLO_BUILD_PACKAGE)
    if not config:
        return
    project_config: Dict[str, Any] = config["project"]
    # Override main [project] configs with custom configs for this package

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/", openapi_extra={"x-custom-extension": "value"})
def route_with_extras():
    return {}


client = TestClient(app)


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


def test_openapi():

```

## Install custom exception handlers

You can add custom exception handlers with <a href="https://www.starlette.io/exceptions/" class="external-link" target="_blank">the same exception utilities from Starlette</a>.

Let's say you have a custom exception `UnicornException` that you (or a library you use) might `raise`.

And you want to handle this exception globally with FastAPI.

# setup.python.sh: Install a specific Python version and packages for it.
# Usage: setup.python.sh <pyversion> <requirements.txt>

# Sets up custom apt sources for our TF images.

# Prevent apt install tzinfo from asking our location (assumes UTC)
export DEBIAN_FRONTEND=noninteractive

# Set up shared custom sources
apt-get update
apt-get install -y gnupg ca-certificates

# Deadsnakes: https://launchpad.net/~deadsnakes/+archive/ubuntu/ppa

  virtual ImmediateExecutionContext* GetContext() const = 0;

  // Following two methods are used to support custom device.
  // Return true if the inputs contain custom device tensor handle. It means
  // that the argument need to be handled by a custom device.
  virtual bool HasCustomDeviceInput() const = 0;

  virtual const tensorflow::OpDef* OpDef() const = 0;

  set -e ; # reset `e` as active
  return 0
}

# runCommand ($@)
# Run custom mc command
runCommand() {
  ${MC} "$@"
  return $?
}

# Try connecting to MinIO instance
{{- if .Values.tls.enabled }}
scheme=https
{{- else }}
scheme=http
{{- end }}
connectToMinio $scheme

{{ if .Values.customCommands }}
# Run custom commands
{{- range .Values.customCommands }}
runCommand {{ .command }}
{{- end }}

 * the symmetry of {@code equals}. Custom definitions of equality are usually based on an interface,
 * such as {@code Set} or {@code List}, so that the implementation of {@code equals} can cast the
 * object being tested for equality to the custom interface. {@code ForwardingObject} implements no
 * such custom interfaces directly; they are implemented only in subclasses. Therefore, forwarding

            Doc(
                """
                The default response class to be used.

                Read more in the
                [FastAPI docs for Custom Response - HTML, Stream, File, others](https://fastapi.tiangolo.com/advanced/custom-response/#default-response-class).

                **Example**

                ```python
                from fastapi import FastAPI